they did ? 1971 was the last year for the big block in the E body.
BUT that said a big block will drop in and it is a bolt in deal. all you need is the standard Big block engine brackets and use the same rubber mounts that are on the 360. Same goes for the trans , bolts to the same crossmember and uses the same mount , if it was a 904 you'll need a shorter driveshaft and 727 specific linkages for the kickdown and shifter.