Flycutting the pistons is the logical solution, but nobody applies much logic to stovebolt modifications- - - -they just parrot the same old advice that's been around for 70 years. Back then, the pistons were cast iron, and flycutting them was not an option for most shade tree wrench jockeys building their hot rod on a shoestring budget. It was simpler to have a machine shop mill the head and sink the intake valve the same distance as the milling job. I remember reading that advice in a Hot Rod Magazine article in the mid-1950's when the 2nd.-generation 235 was a relatively new engine, and the 1957 "high compression" head was something only the rich kids could afford!
Jerry
