Got a new Truck (new to me)

How much rewiring do you have to do in order to ditch the TBI for a carb and electronic ignition? Get an old wiring diagram for the ignition and just do that? Does the old TBI brain over behind the battery have to stay hooked up to run other stuff? When I do the Magnum swap in my truck, I have every piece of under hood wiring, fuse box & computer. I have a wiring diagram to hook up the 4 or 5 wires on the Magnum stuff to make it run. I'm hoping the old TBI ECU doesn't do anything with stuff like heater/AC, lights, charging circuit, etc.