I've done this on several Mustangs and in the process of doing this to my '71.
I have also done this on a 400M, which as many of you know, is a tall deck Cleveland. If injecting a Cleveland is the game plan (and it should be, I love these engines for their excellent heads and lack of coolant in the intake), look to Price Motorsports for intake adapters and choose any 351W EFI intake you want. On my 400 I ran the GT40 351W lower. I absolutely hate distributors, so go ahead and buy a cam sync sensor from Price as well, or build one up using parts from a Windstar van and a 5.0 Exploder. EDIS8 is simply amazing.
For electronics, I prefer the stock Ford stuff. It is extremely well engineered, it is made by Ford, and I have found that it outperforms any EFI system on the market by a wide margin. You have 2 options in this regard:
Option 1: GUFB strategy (A9L, X3Z, A9P, etc.) EEC-IV computer and harness from an '89-93 5.0 Mustang. Certainly the more popular swap.
Option 2: CDAN4 strategy EEC-V computer and harness from a '96 Crown Vic/Grand Marquis/T-Bird/Mustang/Cougar with a V8.
Option 1 is good and can easily be modified to support EDIS8. Option 2 is better, has integrated EDIS8, and supports late model electronically controlled transmissions such as the AODE and 4R70W. Option 2 will also support much higher RPM due to a microprocessor upgrade (higher clock rate).
Both systems are easily tuned using Clint Garrity's Binary Editor software and either a Moates Quarterhorse (recommended) or TwEECer RT. Both hardware units are J3 commanding systems.
I own an '89 5.0 Mustang and the injected 400M is in a '79 Bronco, so I have been tuning these things for over 10 years. My Bronco runs so sweet, it's ridiculous. The 5.0 Mustang is supercharged and the EEC-IV deals with it flawlessly. You own a Ford, look no further than Ford for fuel injection. They have really done their homework.