Grinding starter. New Flywheel and starter.
 

So I installed a new Flywheel, clutch kit and starter. There was damage on the old Flywheel teeth which was expected due to consistent grinding at start attempts. After everything was installed it still grinds sometimes. I tested the voltage from the battery (750CCA) at crank and I get a solid 12V. Then replaced the starter relay. Still got a grind after a few attempts. I seem to have exhausted all options known to me. I keep reading about some type of shim but that only looks to be for TT swaps. I have a 1992 300ZX N/A original transmission and engine.

Any ideas.?

Does it still start when it grinds? or does it grind and not start?
Shims could do the trick. It sounds like you have it all hooked up right.