The Maverick/Comet is a different generation (1970 - 1977) than a 1968 Fairlane. The 1970 model Fairlane (last year model for it, not many were made) was built on the same platform as the first generation Maverick/Comet/Granada would be.
The Granada came out in 1975 and used the same 1970 platform as the Maverick/Comet/Fairlane with some alterations to the attached mechanical bits (different rear end: first year for the aluminum housing, upper control arms...). In 1977 Ford switched to the Fox chassis, which is very different.
Drum Brakes (see note)(depends on the car as six cylinder cars had different brakes than a V-8 version would have, master cylinders were also different simply due to the f/r ratios althought mechanically they would swap) and steering box would have been the same (actually there were different internal steering ratios,...but mechanically they would swap out) for all of them.
NOTE: Granada's never came with front drum brakes. You would have had to migrate the entire from spindle assembly, tie rod ends, drag link, idler/pitman arm from the Granada to the 68 Fairlane. You would also need to replace the master cylinder as well. You could use the Granada one, but it was a power brake unit, so you would need to deal with the vacuum line (no biggy). The real problem is the ESS you took parts from had rear disc brakes as well which means the proportionging valve setup is wrong for a car with from disc and rear drums, so you would need an external proportioning valve if you wanted the brakes to work well together. With the Granada master cylinder you would have been locking up the rear drums in the Fairlane. You would also have to fabricate brakes lines as the fitting sizes between the calipers and drum wheel cylinders are different. The master cylinder fitting is also a different size.
Not saying it was not possible, but it cannot been as easy as you made it sound either.
What you see as impossible or improbable is only a small amount of extra labor and research to me and I've been doing it non-stop since 1978.
The fox body granada showed up in 1980.
The donor granada I used was a 4 door and it was not a fox body.
I sourced most of the brake lines from the ess granada and I don't remember it having rear disc brakes though being a 4 door might have had something to do with that.
I did not change anything on the rear end other than the rear cylinders which were bought new and I believe they had the same bore on both cars.
I pulled parts from several cars at the junkyard as I still do today when I swap engines into cars they were designed for.
The parts swapped were bolt-in except for slight differences in brake line routing but I still used the granada brake parts, power steering box (3 turns lock to lock replacing the fairlanes 6 turns), and sway bars......and they all bolted up.
There was no need to swap the entire suspension for the sake of swapping it so only what was improved by later production date got swapped in.
Most of the stuff I used was from the ess granada but not all of it.
Everything I sourced from the ess version granada bolted in.......why?......because I did my research before opening my wallet.
I finished fixing that cobra's built 347 but I still think it's a low quality kit...........count the lugs.
Before you finalize your cobra's configuration, definately take shifter location and angle into serious consideration as most I have driven are horrible.
This one had a tremec.