TH 350 Shift Improvement Kits?

[kna4977]

Firstly what is the best one? Trans-Go, B&M, or ?

I dropped the pan today on a 1972 TH350. Looks to me like that's never happened before or that it's been a very long time since it was. Tons of crap and sludge and I think rust residue. Likely needs to and will be gone through in the near future. Separator plate gaskets broke apart in places and I will have to scrape a good portion off of the one that is attached to the upper transmission attached valve body portion because it is basically glued on toward the middle of it.

I found no check balls though which is my biggest concern. Would this have ever happened from the factory? What would no check balls cause? Where do I get new ones and where should they go in the valve body?