So I finally was able to remove the starter screws to pull off the starter's face. This was no easy task. Multiple techniques were used w/out success. Finally, success was obtained with the use of an Irwin Hansen screw extractor. See pics below for general interest.
And after more shaving of the modified starter's mounting ring (see pics: modified vs original), I mounted the starter face on the adapter plate and inserted the pinion gear.
I then operated the gear manually to see if gear/flywheel engagement was improved. I believe it was. See video:
https://youtube.com/shorts/e9SCDc5eaKE?feature=shareHowever, I am wondering should the engagement be perfect every time or just on occasion when manually operated?? Will the fully functioning & spinning starter help it slip into gear, better than my fingers simply pressing on the pinion gear?? Ran out of time today to test.
MiataV8 - I was wondering about that as well. Why two ways to locate the starter (inner and outer rings)? I, however, didn't want to mess with adapter plate itself, just yet, since there would be no going back. What if i completely shaved off the inner ring on the starter itself or at least 1/2 of it. would that have the same effect?