5.9 Magnum into a 73Duster

I helped a friend put a 97 360 into a Challenger. When we first started One thing I did was I divided the computer into 2 groups, inputs and outputs. I took all the things that the engine had to see to get it running. Inputs being constant 12, switched 12, tps, crank pos, dist (cam sens), map sens, engine temp. 2 or 3 O2's Outputs, injestors. coil, gen , shut down relay, AIS CEL. There is probly more but thats all that comes to mind. If your donor is from a 96 up and has an auto trans and your not going with the 518, it will set codes and not sure if it will set the CEL. So if thats the case I would change to a Mannual controller.
Are running a stick or auto with this? And is an auto, 904,727 or the 518? Was the controller from an auto or man trans?
One thing he did do is he went with the old style water pump and belts, he also used the old alt with externel reg, which did work but I would just use the alt out from the computer on a new style alt with serpintine belt.

Hope this helps you.