Just find any 78-93 Dodge with a good body. As long as your core support is good, the sheet metal swaps right over. I say if your core support is good, because the trucks to 90 and from 91-93 use a different core support, there is a spot where they made a little more clearance for the intercooler, and the headlights mount in a different position, I want to say higher up on the 91-93. But the body lines are the same otherwise. You can also swap over the doors and sheet metal from a pre-78, but the newer grill won't match the body lines, and they changed the grill in 91 to make room for the intercooler.
For what it's worth, the non-intercooled Cummins had bigger injectors, and often made more power than rated for. Diesel Power's "project rust bucket" in as-near-as-they-could-tell stock form, before they went into it, made 170 horse on the chassis dyno, with 20% torque converter slippage, and they were only rated 160HP. They kept all the 12-valve automatics rated for 160.