You should be able to change the crank, 3.250" stroke for the 230, to the longer stroke 3.530" 250 with out any problems. The bore is the same, 3.875" for both engines. The other parts will all enterchange. If you need to bore the engine, I would change it over to V-8 pistons, flat top 307 ci Chevrolet, to get the compression up for better performance. You can get in to 9.0 to 1 range with just a simple piston change. Joe
