rebuild original
If it were me, I would rebuild the original, If you are in a hurry, and don't care about original, buy a rebuilt one. ****DON'T**** use a used one. Two things I don't mess around with is steering, and brakes. Remember, you are hauling your family around. If you don't have someone locally to rebuild the Master Cylinder, There is a company that advertises in Hemmings. I am going to try them for my power booster and Master rebuild. They are:
Power brake exchange, Inc.
260 Phelan Ave. San Jose, Ca. 95112 1-800-322-1775
www.powerbrakeexchange.com
Hope this helps. Make the right choice. Mike