I did a steel motor mount and it stopped the movement. Just needed one, and that way I don't have to worry about re-drilling both frame mounts perfectly. Also cured the pipe shattering.
Found out that a lot of bicycle axles use m10x1 thread pitch, so thin nuts for double nutting the clutch shaft are out there and pretty available.
Just need more time to get mine back on the road, and see what effect lightening the clutch weight has. I dished the outermost plate on the clutch with the stock weight.