Hemi Swapping a perfectly good 70 Duster

You and me both. That's likely one of the biggest things I'm anxious to learn. I know what it use to MPH in the quarter mile from previous years at Moparty. I'm going again this year, so I'll know right away how the 5.7 compares. I think the weight difference is insignificant, but I'll run it across the scales at the track again to know for sure.
Make sure you report the differences!! Need to see if this is worth doing.