This post is way too late, as I've had the little machine running for about a month now. I've only got about 3 hours since it got going after being put back together, but it seems very strong... much stronger than when it was pulled out. Was able to get a correct driveshaft coupler (a stock one) and a new driveshaft (Thanks to Mr. Hellrung) and it didn't put up much fuss to run again.
Besides a small oil leak (pan gasket) & the paint needs to be re-done (bad primer), it turned out great. I'm really happy to have my little tracotr back after so long. I
really need to get another one so I can work on the one & still have a tractor to use.
As terrible as it is to say, I can't wait for the snow to come so I can really use it. It'll get some use next week to finish up yardwork before the snow arrives then it'll be ready for winter.