Cake...Just did this with an 83...All you need is the efi engine harness on the wiring side...I used a 92.5-93 harness just for simplicity sake, because the fuel pump relay is part of that harness already
Since the harness is basically standalone, all you need is to run power to a few places, couple grounds, and you are set.
I had a tough time finding a spot to mount the ECU, ended up trimming the rear of the glove box door and mounting it behind the dash
Your current dash harness doesnt need to be changed
Fuel system is up to you...i just used a stock efi tank and lines from an 86.
Some nickel and dime stuff...TFI dizzy, thottle cable, etc etc