A 220*cam might power peak at 4800.
1.88s compared to 1.78s? in a 5000rpm engine? IDK if if it's worth it, not to me anyway. But if I did the swap I would for sure notch the bores to eliminate shrouding. Else you may lose more than you gain. Notching is not a hard thing to do; just stay out of the ring-sealing area, and the Fire-ring area. But yeah, IMO, the engine will need to be torn down and thoroughly washed afterwards.
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If you do not yet have heads, consider a pair of Magnums. They already have the big valves in them, and a better port is the bonus. You can run hydros, and adjust the preload with the adjustable arms, to the minimum required to keep them quiet. Jus saying.
