Buy some bluing compound, put a super light coat on the flywheel seating surface ( wear gloves) seat it with the key ways lined up. should be 90% or greater transfer when torqued to spec,
If not lap some, recheck, rinse lather repeat....
https://www.oreillyauto.com/detail/b/permatex-4569/engine-parts---mounts-16774/assembly-lube---valve-compound-17697/161f9b3092dc/permatex-prussian-blue/80038/4610208