Got a 5.4L built up and sold the original truck I had it planned for. I have an 83 I was thinking of doing up and thought about using the 5.4, I have gauges key and computer as well. Doable with a harness, fuel and a trans? (Roughly)

 

I've put a '95 F150 4.9L into my '83 Bronco. I've put a '00 4.6L/4R70W into my '94 CV. I've put an '88 F150 5.0L/AOD into a '75 Bronco. Quint (do some Googling) put a ~'04 F150 5.4L/4R100 into a '78 Bronco. I know a guy who puts LSs into WRXs, S2000s, & even Civics (Google "civette"). I've seen many other radical swaps. It depends how determined & patient you are.

Click my signature & browse the albums to see my '83 Bronco. Click my username at the top of that page to see the other vehicles I mentioned.

 

Well I have swapped from a 4R70W to a 4R100 in a driveway on jackstands so I guess I could be fairly determined. I am currently doing research on slapping this thing into an 88-93 mustang with only videos to see and no actual information so if that doesnt work out I will most likely go this route since I have the motor and the truck.
I am assuming I will have to make my own motor mounts and get a custom set of driveshafts and tear into a wiring harness or get one built?

 

Good luck finding anyone to build a custom wiring harness for something that specific. Even-better-luck getting it to PnP. I only knew of 1 guy, and he had to quit due to health. I spent about a year customizing the harnesses for my Bronco, and I had it here to check. I plan on almost as long for the '93 EB Bronco I'm building now, but again, it's sitting here.

If you decide to do this, take a LOT of "before pics", and then take "during" pics FREQUENTLY. So the next person who wants to know about it can look at YOURS, even if you're not finished yet.

 

There was a guy a while back with a 94ish with a mod motor swap and later turbo it too. Anything is possible