i am planning on going up to 604 ci from 511 ci. what do u guys think of an ohio crankshaft 4.750 stroke product and also would like to know what head would be better 572-13 or b1 originals what flow number differences between both heads- also was told that with the b1 heads i would be able to go with a larger 4530 bore it has better sealing fit than the 572-13 - give me your input thanks