When I built my 389, I had it bored to 0.060 over, but Jim Butler said that it used to be common to bore them to 0.090 over A 0.090 over 389 gives you almost 406 cubic inches. And, you can run later 400, big-valve heads that breathe better. Those heads, with dished pistons, can get the compression down to 9.5 to 1 so you can run pump gas. Give Butler a call and talk it over with him.
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