My brother just finished a customer flathead a few months ago. Many headaches along the way - bad machine shop work, pistons with incorrectly machined ring grooves, carb issues. However, when finished a sweet running engine - unbelievable throttle response, thanks to carb calibration and PV work. Isky 400 JR solid cam sounds fantastic - may be a bit aggressive for a street engine. Superflow600 was used (with some 3.5: pvc piping) to flow test port work.