Hey Britt,
I have a Mustang II setup on my car. From my experience (limited to modifications I have made) the largest determining factor of what calipers you may use is wheel size and backspace on your wheels. I have 15" wheels with 3 1/2" backspace and use 4 pot Wilwoods on the front. There were NO major modifications needed. Just bolt on the supplied rotors and spindles and go (after bleeding the system, seating the pads,ect) I suggest you call Wilwood Tech Line and see what they can set you up with.
HTH
steve