I put apart my first 400 build which was a 499 with indy heads at 275 passes. It made 764 hp and 698tq in the dyno. Aluminum main caps and gridle from muscle motors. I would shift at 6600. It was working fine bearings looked excellent but upon inspection it had a hairline crack in one cylinder and in one of the mains too. I had to change block after that. Good luck!