NEW HT383 crate engine problems

[slow69]

I'm in need of some good opinions/ideas.
I'm helping this guy with an 87 4x4 Blazer put in a new HT383 crate engine. It's in and we are ready to fire it up BUT there is a problem. The flywheel is a 12 3/4 in flywheel and his old one was 14". We've tried 4 different starters for 153 teeth flywheels (12 3/4) but they dont work. The reference book/information sheet gave some gm part numbers for the right starter but the one that we tried did not fit. The inspection cover on the tranny wouldn't let it mound up close enough. This guy is really anal (sorry) about cutting stuff so he's been talking to a million people and he wants to change out the flywheel with a new one. Is there a problem with cutting the damn inspection cover to make this thing fit?
OR any suggestions?