Hey 69chevytruck. I had a similar experience when I put a T5 in to replace my Muncie SM 465 trans that had an 11" clutch. I bought the astro van 11" clutch package which included the 11", 14 spline, x 1" dia hub disc, pressure plate, throwout bearing, and pilot bearing. When I installed it all I got was grinding when trying to shift into reverse, and it flat would not even begin to go into any other gear. I concluded that the bell housing depth on the SM 465 is deeper than an astro van bell housing and the astro van pressure plate fingers did not stick out towards the throw out bearing enough for the bearing arm to push far enough to make adequate contact. I ended up using the astro van clutch disc, but I used the stock chevy 11" pressure plate and throwout bearing. I used my stock bell housing as it has the boss on it for my bearing fork arm. I kept my stock flywheel as it seems to be in good shape. You can use the pilot bearing or a stock bushing, no matter. I also "massaged" the input shaft splines on the T5 just like in the images on Fla54chevy3100 (Dave's)webshots. You must do this!! After that it works.
Hope this will help and encourage you.
EV
