Any brand mini starter is going to be a lot better than the original GM because of the gear reduction. Whoever you order it from make sure it will clear headers or RA III manifolds if that's what you are running. The engine in my car was built by Butler Performance, they installed an IMI-108, 1.2KW starter. My engine is a 461 with I believe 10.5-1 compression. It has no problem spinning the engine over. I have bought lots from Butler and Summit, good service from both places.
FYI, I am running RAIII manifolds from RA Restorations.