It takes a teardown, but the simplest way to pep up a 250 is to install 307 V-8 pistons. The 250 has dish-top low compression pistons, but the 307 flattops are a direct swap. Same weight, compression height, bore, and wrist pin diameter! The last one I built tht way also got a .050" head shave, and still runs OK on 87 octane gas. A RV-type high torque cam also helps a lot in the low end grunt department.
Jerry
