I don't like messing with brakes that are questionable. If it was my truck, I would do what I just did to my truck. I would install a new dual reservoir master cylinder from someone like Master Power Brakes (
http://www.mpbrakes.com/). They can set them up with the lines exiting either side and with a kit, which are avilable from several of the vendors, you can mount it under the floor, like your current one. Then I would get four new wheel cylinders and four sets of new shoes and I would even consider running new lines, especially if your have any rust on them. When I finished the job, I would know I could stop which is almost more important then being able to go! When buying the wheel cylinders, I would try my local INDEPENDENT parts store first. Many of us have found out that new wheel cylinders for these old truck are still plentiful.
Joe
