How About a Gen I 392 in an 87D100

Got an 87 D100 regular cab with a short bed with a good running 72 slant six with a 2 barrel in it. I also have a basically stock with an upgraded cam 58 392 Hemi sitting on the stand. It was rebuilt and assembled maybe 20 years ago waiting for a interesting project to come along. Well, that never happened. Another member and I were discussing the motor today and he suggested maybe pull the slant and use the Hemi in the truck. I do have an early Hemi to 727 adapter and if I did this, I'd like to use a 518 to get a bit better mileage than the 8/9 I'd expect out of the Hemi. So, here's the question and the poll: