I think the B1 572 or B1/MC 572, is the best option. Don't swing that much crankshaft until you have to. That said, if you ever think you might go bigger later, get the raised cam block. Also, be sure to get the drilled lifter bore/push rod oiling mod. For a straighter push rod angle, you might also consider the 2" spread lifter bore spacing too. JMO