There is no doubt that Dr. Diff knows his stuff, however..... here's what you need to do since it sounds you're like me and have a rather low budget. Basically, you want to use a master cylinder from the same car the brakes came from. In your case that would be a 73 ish B body. This will make sure the cylinder bore is the correct size for the calipers. You may also need an adapter to mount it to your firewall depending if its a two or four bolt mount. If you want to go power then you'll need the booster as well. You may need to change out the pedal linkage too, depending on the length. In essence what you're trying to do is duplicate the brake system from the donor car. When it comes to the lines you can use a set from the donor car if there in good shape, make them up yourself, or if you're not up to that Inline Tube is an excellent source. I did my conversion from a 76 A body and used the entire setup, spindles, caliper mounts, calipers, and non power disk/drum master cylinder. The whole system just bolted on. All I needed to do was make up the lines and bingo, I had 11.75" disks up front. Easiest conversion I ever did and the cost was about a third of what a "kit" would have cost. Good luck and happy hunting.