magnum converstion thoughts ??

Wiring the "new" motor to the old car is not is bad as it seems. I have done a few of them, they were all Fords, but most of the EFI harness is self contained. On the ones I have done, as far as connections to the car there was only a few, beyond the hot and ground conections. One of them was to a key controlled igntion wire that is hot during cranking/run. There was also a connection to the brake lite switch, on a Ford, at least I was told, that this kept the motor a steady idle while slowing down from speed, a/c wiring, if you have it. Keep in imind that the swaps I did were prior to obd2, if what you will be swapping in is an obd2 system the harness is a lot more elaboate, but it's connection to the vehicle is about the same. It will be a bit more complicated should you decide to use all of the efi motors gauge wiring etc. I can not stress enough that the efi motor will be VERY sensitive to ground issues, make sure that you ground the motor to the frame and to the battery. The fuel system will need to be addressed, I have seen where a returnless style fuel system has been used, so no return line will be needed. Get everything you can from the donor vehicle, even if you do not think you will need it. Charcoal canister and all. I took the schematics from both vehicles to Kinkos and had them blown up as big as they could go, made tracing wires easier. Pay attention to any shielding that was one on the efi harness, if you do not use it you may have some issues with signals getting picked up where they should not be.