Yes, I've a friend that had a Fairmont Futura with a very powerful
5.0 and a Tremec 5 speed. I don't think I'd personally use an 86 5.0 and
trans, but....

I've got a '78 Mercury Zephyr Z7 that, within the next year, will be
resurrected. (Same as Ford Fairmont) Mine came original with the 302/
C4, but the srod 4 speed overdrive was also an option. It is my
understanding that clutch linkage, motor mounts and a lot of drive
train parts will interchange with the Mustang of that era.
There are also a lot of parts still available from the Ford Motorsport
catalog, especially the double humper transmission mount that you will
need for the dual exhaust. (~$75 if I recall) Another consideration is
dropping in a 429/460 motor. Swap kits are readily available and I
think the swap kit is still offered in the Motorsport catalog. The
catalog cost of $5 is probably one of the best bargains in the world,
IMO.
Even if the Fairmont is about as aerodynamic as a garage, Bob Glidden
had incredible results with that body style back in the early '80s.

That would be a cool build, especially if you had the one with the Landau
bar across the roof with a half vinyl top. They called it the "Baby Bird."

Cars are too cookie cutter these days. It's a good bet that many of today's
teenagers have never seen a Fairmont. I know I've only seen one or two the
past five years myself, and they were both wagons. Another lost car is the
Pinto. I get all kinds of comments from young people when they see my '75
Bobcat wagon that someone converted into Cruisn' Wagon with the portholes
in back.

I autocross with a guy that's built a very cool '80 Fairmont.  Being a Fox
body car it's my understand that EVERY Mustang part will fit with only one
issue ... the car is longer which impacts drive shaft length and subframe
connectors.  I believe he had to change the k-member to accommodate the 5.0
(originally had a 6).  He's still running the 7.5 rear but has an 8.8 ready
to go in if/when the 7.5 breaks.