I converted my '88 LX as follows:
A '95 Cobra donated front rotors, calipers, hub & spindles, rear axle complete.
Also purchased: New 1" bore M/C (93 Cobra), Wilwood prop valve, set of steel '95 Cobra flex lines for the rear calipers, set of '87-93 steel flex lines, MM "prop valve eliminator kit" MMBAK-6, the 3-2 port conversion MMBAK-3, and a pair on new brake hardlines for the rear axle.
I made the .330 tall spacers for the front hubs to Fox ball joints. Bolted up the new stuff, and used the Fox flex lines. They attached to the Cobra calibers with the bolts that came with the calipers with no issues at all. I'm considering some type of tie-back on the driver's side, as they will lightly rub the tire on a hard left turn, but they're Russel, so they're pretty tough.
I used the stock '88 booster. The '93 Cobra M/C bolted right up. No slotting any holes, no blacksmithing the shock tower. (The '93 Cobra M/C seemed the best compromise for my application. One thing to consider in the brake discussion is overall vehicle weight. Foxes are a few hundred lighter than SN's on average. Besides someone beat me to the one in the donor car.) I pulled the factory prop valve off, connected the 3-2 conversion kit directly to the lines that formerly connected to the bottom of it, and moved on to the rear.
I took the stock '95 axle hard lines, cut the flare off at the "tee" end as short as I could, slipped on a compatible fitting for the Fox body tee, and re-flared them. I used new '95 stainless flex lines on the wheel ends and bolted them up to the Cobra calipers. One of the brake tubing companies makes the hard lines already done. Classic Tube maybe? I found this out AFTER I borrowed, broke, and replaced a friend's double flare set.
Being both lazy AND cheap, I was not about to fork over $2600 for the K kit, nor was I going to spend a month of weekends pulling crap off in junkyards. I bought the totaled donor, stripped what I wanted in the comfort of my own driveway (WITH air power), and parted out the rest. I actually made money on the car! Yes, I got lucky that it WAS a Cobra, but you could do the same with ANY '94-'99 Mustang. There are no adapters, cut/welded/machined/modified/redneck engineered parts in the system. I am still experimenting with front/rear proportioning, and will consider pad and rotor upgrades as things wear out. As of now when I stomp the pedal the car stops N-O-W.
Pictures or further details on request.