I believe Paul Forte owner of Turbo Action was the first 727 guy to look at and make better the 2-3 overlap problems in manual shift valve bodies way back in the early 1970 work scope
I'm not trying to take anything away from Mr. Griner, maybe he follow up better on Paul initial work, maybe not shruggy
I wish now that I had bought one of his valve bodies when he was making them, but I didn't whiney realcrazy

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)