Did you see the Tech article in Hemmings Muscle. It has info on what you can use to convert. Check it out. It's in Feb 09 issue. They use rotors and calipers from a 78-79 Cordoba. All you need to find are the caliper brackets and 73up abody spindles. The calipers and rotors can be found at most parts stores. Hemmings did their conversion on a 64 Dart.
