One pretty common mistake a lot of mechanics made back when there were a lot of stovebolts on the road was putting the clutch disk in backwards. Look at the old clutch disc, and you'll see there is a little bit of difference in the front and back. If the side with the springs sticking out a little further is installed toward the flywheel, the springs will rub the flywheel attaching bolts, and the clutch won't release. Been there, done that! I'm not saying that's your problem, but it's a definite possibility.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!