Agreed I have very much considered! I will say this (which has prevented me considering further at the moment): there is no engagement issues (always engages and spins without drama), no visible to me unusual wear on starter pinion/bendix gear drive surface (just the wear marks on the tip where its touches the running spinning flywheel). Starter is quiet and identical in noise to my first FRS. The wear pattern on both the flywheel and bendix gear appear to be even and consistent with what I imagine is healthy good engagement (ill get a better look at flywheel when it comes off). No damage to either mating surface and no unusual rocking or movement in the 2 machined surfaces of the starter or the tranmission when installing the starter. The trans install itself is about as challenging as any trans install is on the garage floor of a small townhouse 1 car garage
It is of course not unreasonable to consider the possibility that the bellhousing or block may have a misalignement but that a pricey and challenging to verify I think..
But I will keep this in mind as I pull it apart again and check the flywheel closely for signs of uneven or angled engagement and maybe run a straight edge over the bellhousing surface.
I am going to try purchasing the exedy aftermarket oem equivalent flywheel, it looks like a quality piece (and about $150 less). If this one develops ring gear problems, then it will be time to consider warpage in the big cast parts!
I have decided to go with at this point ring gear stretching due to overheating of the cast iron portion of the flywheel as the culprit for time being. I do know for a fact this flywheel got hot enough to give a torched patina too much of the flywheel. Im pretty a sure the ring gear is probably a hardened steel of sorts so it may not like being stretched and there is likely a heat propogation delay considering the poor heat transmittance characteristics of iron and steel. I also doubt its that often that people torch clutches to that extent (the clutch got so hot it literally disintegrated into carbon dust and fibreglass, and yes I had a long conversation with the current owner about wether her knee could handle this anymore and proper slipping RPM). I shouldnt have reused the flywheel but it looked great after turning.. sorry for the novel!