Hemi Swapping a perfectly good 70 Duster

Personally, I think the only thing wrong with a 5.7 is the cam. It's better than a stock 5.9, but it is similar in that it just kind of falls on it's face at about 5200 rpm. Put a mild cam in it and it no longer feels like a truck motor. That's why mine is getting a 6.4 M6 cam.
Agreed.. 5.7s are great little motors. I put a 6.4 non mds cam and lifters cam in hoopty with a hellcat oil pump. It's a great no tune option