650 at the wheels is stout! Anything over about 450 wheel and it’s spin city on the street.
Low timing, a slightly rich AFR, and sneaking up on boost and they will last. Good news is there in low demand which makes then cheap.
I wish we could find magnum 360s in Australia but they are very rare as they were never released here. I shipped mine from the US.
I gapped my rings at .028 top and.030 second ring. Had no issues and no blowby until I cracked the piston. Wish I had a few more short blocks here.