SB, I just read your post & it seems your looking at something else now... That's kewl, buy what you feel will work best.
I can tell you that those years were good for Chevs! Those straight 6 engines are bullet proof just like the Ford 6's! Chevy parts tend to cost less & be more plentiful than Fords because they're more interchangable from year to year, (Ford parts are more year specific.)
I love my 64 Chev!