Another 90-302 into 65 mustang

IT should be fairly simple I f you have both complete cars. There are differences between the Mustang and Mark VII engine management, but nothing too complicated. Transplant all the wiring, find a place to locate the computer, and it should be plug and play.

Much easier if you have the complete car. The first thing you want to do is buy a Haynes or Chilton manual for the Mark VII. This will allow you to strip all the circuits you don't need out of the Mark VII wiring harness(EVAP, EGR, etc.). The wiring diagrams should show you which wire gives you ECU power etc etc....but really there are no crazy anti-theft circuits in those early ECUs, its pretty straightforward. You do have other considerations though...such as the intake manifold...what are you going to do for shock tower bracing? The EFI manifold does not fit with the factory bracing, and bad things happen if you ditch the braces.

I would not give up so easily. There are plenty of people with 5.0s in early Mustangs. You can make the braces with heim joints and rods and some fabrication. If you have the whole car, you can put the engine in and have all the little things to go with it. Pre OBD2 (which you have) is easiest to deal with. If you don't want to redo a stock harness, there is aftermarket. But if you don't mind some wiring, you can save money by using the harness you have.

Pretty much bolt original exhaust manifolds to 5.0. Use original Mustang motor mounts. AOD requires a different rear support. You can keep your speedometer by adding it to the VSS sensor although I found the original cable to be a bit short. Driveshaft will need shortened but the yoke is the same as a C4 or Toploader. Convert to front style dipstick (drill hole in late front cover) and use an original front sump oil pan and pickup. You will have to add an O2 sensor to each exhaust pipe in the H-pipe. Fuel pump I would get a Tanks inc tank with sump and be done with it. Otherwise you will have to add a return bung and use an external pump (either way you have to add a fuel return line). Other than that it is mostly wiring. I would also convert from the 2G to a 3G alternator "while it was out".

I put an '88 Cougar 5.0/AOD in my '66 and got it running before swapping to an '00 Explorer 5.0/4R70W.