well i will add to this by saying this .try to stay with the same year chevelle like engine frame mounts. engine mounts. headers. oil pan .some of this stuff works up to 70+ but if you get a 350 or 454 out of a truck the pan will not work. or if you used a full size chevy car pan them pans will not fit the front cross member and you will need all the power brackets for the chevy and stay with one year pulleys with that year water pump and steering i have put over 12 bbc engines 3 tall decks big blocks 572+bbc in my goats both 66 and know a bit about this if it was mine it would be big block if that helps