I have owned my 78 Fairmont since 1986, and raced it with 427/428 FE engines from 1988 thru 2016 or 17, both with a C6 and a Jerico 4 speed. I believe that the 83-86 Thunderbird engine compartment is identical to the Fairmont or FOX Mustang. When I was building my Fairmont, there was no such thing as commercially available aftermarket tubular front K members, so we modified the factory K member. We made our own custom motor mounts, modified a factory FE 4x4 rear sump oil pan, to work with the steering rack, mechanical clutch linkage, and over the years, had 3 different sets of custom fabricated headers, one set made by fellow forum member Tom Posthuma. As for wiring, I retained the factory alternator, and used all the factory wiring from the original engine (my car was a factory 4 cylinder car) with the FE. Although I am currently running a 347 SB Ford engine, with a G Force 4 speed, and a tubular K member, with factory lower control arms with the coil springs in the original location. Not sure how the height of the engine to hood clearance compares from Fairmont to Thunderbird, but my stock flat hood would have closed with a lower height intake manifold, and Len Schneider used to race his Super Stock 84 Thunderbird with a 428 CJ when he first started racing it around 1984 , and it fit underneath the stock hood, although he has been running 351Cs shortly afterwards. The FE has much more working room under the hood of the FOX than my previous 68-69 Fairlanes and 69-70 Mustangs, although the wide, angled lower control arms do make routing header tubes challanging, at least with the factory K member.
