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Getting ready to order a KB block and I,m wondering if I should build a 572 or 604. Reason being I only have some max ported by MCH B1 original heads with individual shaft jesel rockers. Will they support a 604 or would a 572 do just as well? And should the lifter bores be bushed? Any advice would be appreciated.
Allen

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I would doubt they would work very well on a 604...
if they were the M/C then they would... but they
would still work to a lesser rpm .... thats a lot
of flow you would need for the 604 and the revs
EDIT
I would think the originals would even be on the small
side for a 572(even fully ported)..... JMO... I was
going with the M/Cs on a smaller ci but was gonna
have to rev it higher to make them efficient