What engine would you build for a Ramcharger?

I'm leaning more towards the 318 since you drive it so much, built the same a 360 will get around 3-4 MPG lower but obviously has more torque and power. Also think a roller cam is the way to go, they have a lot less friction at low RPMs = fuel economy.

My idea: rebuild the roller-cam 318 with whatever it needs to be solid and reliable and get a mild reground cam, something similar to the factory 5.2L Magnum cam. The 318 LA roller cams were literally the exact same as the flat-tappet engines (TINY), just designed for use with roller lifters. I had a 1988 Chrysler Fifth Avenue with a roller-cam 318 and it was smooth as silk, quiet, and grunty right off idle but ran out of breath around 4000 RPM (after I had converted to 4-bbl and dual exhaust), not like you'd need any more RPM but I think a modern roller cam profile could get you more torque across the whole RPM range. Add the Performer intake and Eddy carb and you have a 100k-mile truck that will go anywhere reliably. And get decent mileage at the same time.