I believe Tamiya has actually done two 1/700 Yamato kits. The first came out in the early seventies; it represented that state of the art at the time. But it pales in comparison to the retooled version, which was released just a few years ago and, for my money, is one of the finest of all 1/700 scale styrene kits. It's a real masterpiece. The number on the one I have is 31113. I believe the company recently re-released it in a fancy box (and at a higher price), to coincide with the opening of a Japanese movie on the subject, but as I understand it the contents are identical. Your list of three numbers includes 31105 twice. I suspect that and 89668 are the old seventies kit and the reissue of the new one, but I don't know which is which.
You didn't mention one aftermarket part set: the one from Gold Medal Models. I haven't seen the others, but I can highly recommend the GMM set. It includes such things as the railings for the tops of the secondary gun mounts, beautifully done radar screens, and guard rails that, under sufficient magnification, can be seen to distinguish between wire and chain rails. (I found that hard to believe, but Mr. Perry demonstrated at a booth in a IPMS convention that it was so.) It's hard for me to believe that any of the competitors' sets could be signficantly better.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.