I am actually very interested in what you're saying... Please go on
I'm not sure if you have followed some of my exchanges with Ben Masada, but we have gone over some of the core issues where a different light is shed upon things. To get more of the nitty gritty stuff I'll take a few minutes and PM you links to them.
For the sake of other readers, who may not be that ambitions to follow Ben and I hashing things out, I'll give a rough draft here that includes a bit more than I have shared with Ben thus far.
Joseph Smith Jun. held that all the tribes of Israel would in time be identified and gathered together again under a political kingdom. The process by which this would occur was through direct revelation through Prophets who acted in accordance with the mind and will of God, not on their own reasoning. Thus, it wasn't just men on their own would have to figure it out unassisted. God would actually initiate these actions much as He did when He called Moses of old to lead the children of Israel out of bondage.
So, when the time was right, God would again call a Moses in the latter days to reassemble the scattered remnants of the people of Israel who were driven out among all of the Gentiles. Before it went to the House of Israel in a specific manner, God would first initiate this among the Gentiles and give them an opportunity to be a part of what God would definitely, without question, establish for His people in the not too distant future from then.
So, prior to the time the people of the northern kingdom would be 100% eligible, the Gentiles would have a period of time to qualify to receive the Kingdom first. I base the timing of these two dates on Daniel's 2,520 year period and on Ezekiel's 2,730 (390x7) years of judgment that is found in chapter 4 where God says they are going to be scattered among the Gentiles for all that time.
So, after 2,520 years were expired, the timing for the Gentiles to have the kingdom would arrive and then the "one like unto Moses" would be called to initiate this opportunity to the Gentiles. This is who Joseph Smith Jun. understood himself to be as his ministry coincided with this first timing factor. He considered himself to be the 'rod' from the stem of Jesse acting in the capacity of Ephraim to perform the duty of the birthrigh tribe, which was to gather the people.
Among the things he established, church patriarchs were given special priesthood responsibility to receive revelation from God as to which tribe of Israel the people being gathered in belonged to. In most all cases those who became converts and members of the church were found to be of the tribe of Ephraim. Thus, the Mormon people can in large part be known to consider themselves Ephraim in what you might consider a collectively resurrected state.
Among the duties Joseph Smith Jun. received, he was to be all three capacities of Prophet, Priest and King to the people. He was the Lord's Anointed "Elijah" who would receive oracles directly from the Lord. A little known aspect of Mormonism is Joseph Smith was also made king of the political kingdom of God. He literally considered himself to be the King over all Israel with the charge to assemble the outcasts into Zion, which as you surely know is not a small claim. He was also the presiding high priest of the religious organization. Thus, Joseph Smith Jun. was also a King-Priest "Moses" figure as well. We only find a precedent for this in history by looking at Adam himself and perhaps Enoch as well. Not sure about Noah.
Another very little known aspect of Mormonism is the economic system Joseph Smith Jun. endeavored to establish. Had it been left unmolested and been able to get past its early growing pains it would have caught on like wildfire. In fact, the progress financially of the saints caused a lot of their hardships because others around them felt threatened by their rapid growth, prosperity and progress. It was purely biblical based in that there was a tithe component as well as an inheritance component. It strictly prohibited usury, and I could go on. But, none the less, all of these claims do have a foundation in the OT that require a greatly expanded perspective on it.
Unfortunately, the Gentiles rejected their opportunity to have the Kingdom of God, the one Jesus told them to look and pray for the coming of, and suffered Israel's King (in his own eyes and that of many others) to be put to death. The Gentiles have since persecuted it (the Kingdom) and chased it into the wilderness and are resorting to every device they can muster to stamp out everything non-worldly that God had Joseph Smith Jun. establish in it. The world won't be happy until they have reduced Mormonism to a toothless sect of Christianity.
ADD: [Since Ephraim brought with him his old tendencies in his resurrection, the Gentiles have almost succeeded in ruining them. Unfortuantely, Ephraim has been resurrected unto pretty severe condemnation and has backslid again, which shall result in the name of his tribe being blotted out per the terms of Deuteronomy 29:18-20, along with the attendant cursings. Very dark and woeful times are ahead for Mormons. They do not realize they are fallen and in need of redemption and have pretty much made a mockery of what they were given.]
A careful examination of some of the passages in Joseph Smith's revelations will directly give interpretation of OT passages. For example, in Doctrine and Covenants section 113 a question is asked about Isaiah chapter 11 and what the stem, rod and branch mean. I'll quote it here for your consideration.
D&C 113
1 WHO is the stem of Jesse spoken of in the 1st, 2d, 3d, 4th, and 5th verses of the 11th chapter of Isaiah?
2 Verily thus saith the Lord: It is Christ.
3 What is the rod spoken of in the first verse of the 11th chapter of Isaiah, that should come of the Stem of Jesse?
4 Behold, thus saith the Lord: It is a servant in the hands of Christ, who is partly a descendant of Jesse as well as of Ephraim, or of the house of Joseph, on whom there is laid much power.
5 What is the root of Jesse spoken of in the 10th verse of the 11th chapter?
6 Behold, thus saith the Lord, it is a descendant of Jesse, as well as of Joseph, unto whom rightly belongs the priesthood, and the keys of the kingdom, for an ensign, and for the gathering of my people in the last days.
Not all Mormons interpret this passage the same, but it at least definitely pins down some items in concrete that indicate the tribe of Ephraim and of Joseph do indeed have a very critical role to play in the latter day restoration of the lost tribes of Israel. It is also interesting to note that these two individuals being prophesied of also have the blood of Jesse in them.
ADD: [Thus, the promise that all the kings on the throne of Israel would be of his seed is being honored. Joseph Smith Jun. then takes the position that the scepter departs from the House of Judah and goes to the House of Ephraim and the House of Joseph in the latter days. Thus, he asserts the position that the Messiah the Jews are awaiting shall not be from the Jewish people but rather from among the remnant of Israel of the House of Ephraim and again from the House of Joseph. Thus, he upholds the 3 Messiah concept that I know some Jewish scholars have seen a basis for.]
And, there is also much said about how Joseph (tribe of) shall be who ultimately brings the fullness of the Gospel and the Kingdom to the dispersed of Judah and enables them to overcome their adversaries and be established again as a people who shall be able to live all of the laws of the Torah, except at a higher level than the carnal commandments of the lesser law they were given anciently. The laws shall all remain but it will be the same shift that Jesus spoke of. Instead of "thou shalt not kill", it becomes "thou shalt not be angry", and so on. The law is there, it just applies at the spiritual level. The great high priest is who raises the people up and saves them from bondage and from carnal commandments.
Anyway, I think I've pretty much rambled on long enough. I realize I have only given scanty references. Please drill me for anything you would like better support for as I sense you are looking for passages in the OT that are seen in a different light. This at least gives you a conceptual overview we can now pick to pieces in detail as much as you would like.