I converted to discs in front and all I had to do was install a master cylinder from a 71-72 chevy 1/2 ton pickup. It pretty much bolts right up. You can score one at a junkyard, which should come with a prop. valve, for about $25, which is what I did. Most auto parts stores sell the master cylinder for $15-25 rebuilt, which costs less than buying a rebuild kit for the used one. Just pick what works best for ya! Also, the manual brakes are working just fine for me. If you do want to install a brake booster on your six, all you have to do is tap into the intake manifold, if one doesn't already exist, install a vacuum port, and hook up the booster. I takes all of 1/2 an hour to modify.