boring a JDB block

4.5 = 4.500 + 0.045 = 4.545 is a lot smaller than 4 11/16 = 4.6275. You need a 0.1875 overbore to fit those pistons.

Unless I am missing something?
It would be just under a quarter inch , so 1/8 inch per side. I don't think you will get into the water jacket yet. But what about the head gasket??

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