I am looking at a 68 pontiac 400 block casting number 9790071, but it has a YE engine code; does anyone know what engine this is (HP rating, head number- it has 4X heads on it, and I want to try to get the original heads); I do not see that engine code (YE) for the 68 pontiac 400. The guy told me that it came out of a 68 Bonneville.