There are people that have done this successfully. The main issue is the wiring harness for the computer and the cost of parts. To the best of my knowledge, there isn't a bolt on and go junkyard parts list for this swap. There are a lot of other parts besides the computer & wiring harness.
The simplest way is to spend $550+ bucks for a swap harness made to put the Mass Air EFI system on older Mustangs. It works, and you'll have all the parts except the A9L mass air computer and MAF in the kit.
See
http://www.cjponyparts.com/ford-racing-engine-harness-efi-for-5-0-liter-engine/p/M12071A50/?
The other alternative is to rob an 86 5.0 Mustang of all the EFI parts and go speed density.
The A9L or A9P computer is selling for $100-$150 depending on where you buy it.
The MAF if you decide to go Mass Air is another $40-$100 from the j/y.
If you aren't feeling pain in the wallet long about now, you're either numb or have lots of $$$
If you get really serious about this conversion, add another entry to this thread and I'll see what I can look up and find.
Check out
http://www.bcbroncos.com/fuelefi.html for some quick help.
Some help with fuel injection lingo...
Speed Density uses Manifold vacuum (MAP), Throttle position (TPS) and RPM, & Air Temperature (ACT) to guess how much air the engine is pulling in. Then it uses all of them plus the O2 and ECT sensors to calculate the air/fuel mixture. It is dependent on steady manifold vacuum and minimal changes in airflow from the stock engine configuration to maintain the proper air/fuel ratio. Change the airflow or vacuum too much and the computer can't compensate for the changes, and does not run well. Forget about putting a supercharger, turbocharger or monster stroker crank in a Speed Density engine, because the stock computer tune won’t handle it. Every time you seriously change the airflow through the engine, you need a new custom burned chip to make the engine run at peak performance.
Mass Air uses a Mass Air Flow meter (MAF) to actually measure how much air is being pulled into the engine. The computer uses this information and inputs from the O2, TPS, ACT, ECT, RPM and Barometric Pressure (Baro) sensors to calculate the proper air/fuel ratio. It is very tolerant of changes in airflow and vacuum and tolerates wild cams, high flowing heads, and changes in displacement with minimal difficulties. Larger injectors can be used with an aftermarket calibrated MAF or a custom dyno tune. This makes it possible to use the stock computer with engine displacements from 302-408 cu in, and make many modifications without a custom dyno tune chip. Put a new intake manifold on your 331 stroker and the computer figures out how much more fuel to deliver without having to have a new chip burned to accommodate the extra airflow.
Here's a book that will get you started with how the Ford electronic engine control or "computer" works.
Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.
It's about $25-$50 from Borders.com see
http://www.amazon.com/ . Select books and then select search. Use the ISBN number (without dashes or spaces) to do a search. Try searching using M-1832-Z1 instead of the ISBN number if you don’t get any positive results. You may only be able to find a used one, since the book is as old as the cars it covers. Or you order it from your Ford dealer as SVO part no. M-1832-Z1.
Use the ISBN number and your local library can get you a loaner copy for free. Only thing is you are limited to keeping the book for two weeks. It is very good, and I found it to be very helpful.