Just a thought---
When I acquired my '63 F-100, it had already had a 390 swapped in. The truck originally had a '6' and automatic. EVERYTHING had been sorta cobbled together and nothing quite fit and many of the parts were worn out. One of the things I didn't cotton on to right away was that the bushing (brass two piece) in the block end of the Z-tube was badly worn. I found that I could source one that was supposed to go in a '57 T-bird and replaced it with a goodly amount of grease. It only lasted a couple of months. In order to fix it, I ultimately replaced the ball-headed stud on the block bracket with a bolt through a Teflon 'doughnut' from a later model car.
I never was completely satisfied with the clutch action even though I'd re-manufactured just about every piece of the linkage. But with Heim joint ends and hardened bushings in the 'wallered-out' holes, it was much better than when I started. Good luck to you!
KS
