Durango Hemi harness

Reading a lot of the threads on here and figure this is the place to get some answers. Was given a 2004 Durango all wheel drive with a Hemi for free and plan to place a 1940's Dodge pick up body on it. It's going to be a lot of work but that's the idea to keep me busy. Does anyone know what I need to keep to be able to run the engine and trans. I have the wire harness from the engine compartment along with the ECM. Do I need to use the engine compartment fuse panel and the one in the cab for the engine to run properly. Also have the ignition key as well. Someone cut the wires to the foot throttle so will pick up one at the wreckers and splice it back on. Any ideas on what else I could use from the Durango before I get rid of it. Never done this before so I'm going to need all the help I can get on this.