I have a 70 chevelle 350 with a th350 trans. I changed the intake and carb with a edelbrock performer and a holley 600 carb. When I hooked up the kick down linkage to the carb there is no play, it connects at the very end of the linkage. Will this affect the performance or longevity of my trans.

What do you mean by no play? There is a locking piece on the kickdown cable collar that goes into the bracket. You pull up on the lock to allow the body of the cable to move so that you can adjust the travel such that the cable is fully pulled at WOT. Fairly simple procedure and outlined in a lot of different transmission and car repair manuals.