We used a stock one with mains cut down in Lenny Meltons KOS Dart--it finally made some mid-upper 8 runs all on big NOS--ran for years --suffered through a 727 explosion, bad tuning guessing and I don't know what all until finally getting a super tune up then it just ran and ran and ran The 400 stock block had two bolt stock main caps and is STILL running.
Good tune up--timing right, no detonation and never worry--I have always felt they were stronger than the block.