Wire up a 5.9 FI Magnum to 60's A body.

I don't think it is really all that hard. Find a service manual with wiring diagrams and start tracing wires. You will need a constant power and a switched power, and will need to wire in an ASD relay and fuel pump relay. I think that is all to make it run. Not 100% though, been a long time since I worked on mine, but that should be close.

There was a separate computer (called a CTM - Central Timing Module, I think), but it isn't needed to run the computer provided it isn't the highline one with security. Worst case, get your PCM flashed to remove it and don't run it. I have planned to run one and use the security feature, really just needs power, ground, the network wires and a signal from the door lock or a fob.

If you don't care about a CEL, ignore the emissions canister wires. If you want the light, then get the emissions checks out of the PCM or mount the canister somewhere.

For the trans, make sure to run all the wires. Pretty simple. PCM might need a speed input, but it might shift fine without it.