I opted, following suggestions from Jim
inject usa many years ago, to use a 1990 Camaro ECM that I bought from him, along with a blank chip. Jim was a great resource, though others can alter a harness. the ECM is still in the original location.
I also sent my harness to Jim and bought the few sensors needed. It's a big job. Remember to change all rubber in the fuel feed lines leading from the new, higher pressure fuel pump in the tank! I had a burst; the one inside the tank, TG, and Jim answered his phone and suggested it as the no-start problem from 2500 miles away!
You may know that the fan shroud is different, along with many other underhood pieces, in '84 vs later cars. Then, I wanted my car to look like an '87 and get cooler air into the SuperRam.