You need to be a little careful here in order to avoid a common trap. If you use a standard master brake cylinder from 1967-1972, the bore of the cylinder is 1-1/32" in diameter, which pushes too much volume for a comfortable and predictable braking experience. This large bore diameter is so that with non-power brakes the pedal is easier to push. If you put one of these in front of a vacuum booster, you'll get the infamous on-off brake problem common to power brake conversions. That is, every stop will be an emergency stop.
The right thing is to get is a master brake cylinder for a 1973 model specifically for power brakes. I picked a new one up at NAPA. These have a 15/16" inch bore, which pushes less volume of fluid a further distance. It has also has the dual-reservoir setup. Take some time with the parts guy and make sure you get the right one, because NAPA shows several variants of the same thing. I know on-line shops will give you the detailed specs also.
Something else to consider, something that took me a while to find out, is that remanufactured brake cylinders often have their internal check valves removed because they're too impractical to rebuild or replace, so they're simply removed. This can also increase the pedal travel before you feel any braking action at the pedal. New brake cylinders don't suffer from this issue because the check valves are still there (assuming the unit is designed to have one). We found this out during a Mazda Miata project, but only after getting an auto parts chain store regional purchasing manager to confess this information at a drunken wedding reception. Later, I experienced the same issue on my Scarebird front disc conversion.
Last, I'm not sure if the SSBC kit needs this or not but if you get it all hooked up and find that the pedal travel still takes too much distance to engage, you can do what I did and add a 2lb check valve for the front brakes and a 15lb check valve to the rear. You shouldn't need them if you landed exactly the right brake cylinder. All of this depends on whether or not you actually need it. I've done a couple of front disc conversions and I needed the check valves in one project, but not in the other.
I hope this helps you.
