JFZ brakes.

I have jfz brakes on the nine inch in my car, and I'm almost positive I've got a stuck or sticking caliper. Does anybody know of a caliper rebuild kit still available? (Four piston).or, would a wilwood kit work? I have not yet pulled the caliper off the car.
I think I can get pads (which I don't need) and used calipers, but I would rather just rehab the calipers I have now. (I wish I knew the piston sizes.....).