The 331's had main bearing problems, especially in the pre-1955 models. They're also very hard to find stock parts for, and speed parts are just about nonexistent. The 390 is a very good engine, but the newest ones are 1962 models- - - - -pretty old for a daily driver. The 429, 472 and 500 engines are very powerful, still pretty plentiful, and only slightly heavier than a Chevy small block engine. I've got a 472 and a 500 that will find their way into project trucks before too long.
Jerry
