I want to rebuild and install a 455 in my 71 cutlass. I have located a 455 that is either a 1974 or 1975 Toronado engine, out of a camper. The owner has told me it has "J" heads. Is this a good engine to work with, or should I be searching out an earlier engine. I was told I should be looking for "G" heads...does it really matter? for performance and or resale value?