Do you have an auction number for it?
I have looked at the inside of each rotor, but not back to back.
I once had an '87 that would fire for a while, then run poorly, then it wouldn't run at all. The flywheel key was sheared. It may have just been off before it broke.
Some sort of modern and mid-80's combo would be great to get one of the older models back up and going again.
I doubt anything would be done on the rotor side. It must be some stator mod. A used rotor off a modern one and a older stator to use as a test bed would be great.