Had same problem on the boys mk2 scort ended up binning all combrake stuff inc pedal box the same old excuse "it should fit, it does fit, never any complaints" spiel. Shame really i thought the calipers were the bollocks so upgraded to compbrake. Someone off here was starting to help put together another kit for my Alfa and he disappeared too.
No idea whats going on but save yourself a headache goto rallydesign and buy wilwood like i had too its better thoughtout pedal box and it fits without hitting anything. Shame really i gone full circle back to wooly wilwoods which are shite on tarmac.
ps smaller master for front, larger for rear and try get as much rear bias as possible before locking them up with wilwoods the bar nearly central (did it at mot station on brake test rollers for a drink)