Re: Mustang HO in Non HO CV
We installed a computer controlled DOHC 4.6 into a '68 Mustang over ten years ago using a stand alone harness. We used a 5 speed Tremac (not an auto, but still a non-computer controlled trans), and as far as I know, the car was dependable with no problems associated with the wiring. Your non-computer controlled automatic will not know what's in front and will work fine as long as it is is in good condition and can handle the extra torque.
Our harness was custom made by a SoCal auto electric shop that wires SCORE off-road racers. It's just a matter of connecting the sensors to the PCM (easily said), but sometimes the PCM will need to be programmed. That's where I get lost, but ask around.
The shop I used has since closed, but there are many others. Check around your area and with some of the local hot rodders at cruise night. They will steer you to the good shops that do custom work. Also check FRPP. The FORD stuff is expensive, but reliable.
I would be inclined to swap a big torquey 460 into your heavy ride, but since you already have the engine, the HO sounds like fun and has the makings of a real sleeper.