Pryor to 1988 or so you could get preformance pads for your calipers but once Ford upgraded the stock brakes on V8 Mustangs in 1987 most companies dropped the 4 cylinders pads and only offered the V8 pads.

I had a 1986 V8 Mustang and I had the same small 10 inch rotors and calipers that the 4 cylinders got so I know what your're going through!