[Coloradocobra]

A related item to end-float and the bellhousing/block plate is starter gear clearance. This is a long-shot but can be easily checked since you intend to pull everything apart. Pushing the pressure plate will drive the crank forward slightly and if your starter gear clearance is marginal it may hit. When I installed everything I turned the crank and could hear the starter hitting the flywheel. It was close and was probably caused by stack-ups including the flywheel flange machining, the block, etc.

A standard starter shim solved the problem. In your case, it may all clear until you push on the clutch. Pull the starter and inspect the end/face of the gear as well as the flywheel gear to see if there are any signs of wear. It could be that it is so close that it was not a problem before your work and appeared when it was all put back together again.

Can't hurt to check...