Is there excessive clearance between the bearings outer race and the bearing bores in the clutch bell?

I had a clutch that would do that...and even w/ new bearings I could wobble the clutch bell. The bearing bores were too big (just a couple thou. ) but apparently that was enough to cause problem? You have a lot more powerful engine than the one I had, as well.

I put a new clutch bell on it and that stopped the bearing problem.

Don't know if that's gonna fix your problem, but it's worth a shot to measure the bearing bores to see? Can you wobble the clutch bell even w/ new bearings?