I have a used 6 bolt Fidanza sitting on a shelf. It went through one clutch failure with a spring bouncing around in there. The result is that the non-clutch mating surface is marred up. I can't seem to measure accurately enough with a set of calipers to make the call on how close it is.
Attached is a picture of the flywheel and you can see the beat up inner surface.
I will sell it for $70.
Worse case, it costs $60 for a replacement surface plate from Summit Racing.