I believe the 230 and 250 cranks will interchange. The blocks are basically the same. You'll just be making yourself a 250 engine, which will probably get you more power gain than hotrodding the 230. BTW, 307 V-8 pistons fit the 250, and convert the 250 dish-top pistons to flattops, with a good compression boost. The last one I built that way also got a .050" head milling job, and it still runs OK on regular gas. Find yourself a good 250 crank, and grab a set of 307 pistons.
Jerry

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