Thanks for the advice on the trans, I may have to break that 350 open sometime and check out what's wrong with it. I believe I have a gear with a broken tooth. It would pop, under a load, what seemed like once every rotation of the gear...I had thought it was a broken tooth on a sprocket at first but that wasn't it.
Anyways, I think I may just jackshaft the 600, if I can find some cheap or free parts to do the job. If not, I may have to consider an alternative. It makes it a real challenge to do this build for less than $100. Items that have been purchased prior, that you have lying around, don't count towards the total. As well as donations wouldn't count either, those are "free" items.