354 or 392? Hemi? Questions?

I say give it a shot. Remember, those early Hemis are more of a Hemi than the 426s were. The heads on them are TRUE hemispherical heads. The 426s were really not quite there.....they just got the cool name and all the marketing gimmicks. Is the 331 worth it too?? You bet! Seems I remember that they also use the same timing set as the small block, too. Somebody feel free to slam me against the wall if I remembered that wrong. Usually when people say stuff like "don't do it" "it's not cost effective" and "nobody makes parts for that" that just lights my fire that much more. As Mr Lusk pointed out, people were doin this swap in A bodies long before any kits or fancy rack and pinions were available. It ain't gonna be easy and it's gonna be time consumin. But if you stick it out, in the end, you'll have sumthin unique and sumthin that YOU built. Go for it dude.