BuddyJ,
As you well know the master, I believe, is part of the power booster.
You will need a new style dual master that has two seperate circuits. One front & one rear or as you are calling it a "split" master.
Do yourself a favor & just get a metering block. Does the same thing as a proportioning valve & MUCH easier to install & plumb. Speedway Motors has them. ASK THEM for directions on how to hook up the lines OR I could sell you one with an arrow from where the line from the master goes.
As for a booster you will want to get one which includes the master cylinder. The reason for this is that the correct master with the correct depth
for the power booster being used is already, supposedly, set up clearance wise for the combo. This is very IMPORTANT because if the clearances are too tight, after the brakes warm up, it will be like driving with your foot partially on the brake or IF too loose you could end fighting a low brake pedal.
You will need to measure the center-center distence on the power brake booster studs. I don't think anyone makes a booster with the same center-center distance as the original so you will more than likely have to elongate the mounting holes in the firewall.
Then from there it's just a matter of getting the plumbing done. Now I'm going by memory here so excuse me if I'm not exactly correct.
Right now the line comes out of the master & goes to a junction lock on the frame. Two lines go to the front brakes & one to the rear. The one going to the rear remove the line. Now the line from the master for the rear brakes, don't know which one because they change with the type of master your supplied. You run a line from the master & using a coupler just connect the line from the master directly to the rear line. Install a plug in the junction block from where the rear line was removed. Now for the front discs you run a line from the master to the junction block. Plumbing done. Once you get ALL the correct size fittings now all you have to do is bleed the system. It would be easier plumbing wise if you just use the metering valve to plumb for the front brakes instead of the original junction block. Simplifies the nec. plumbing.
The only other thing I can tell you is to put a couple of curls/coils in the brakes lines coming out of the master. The body of the car & the frame are cushioned with rubber mounts & believe it or not there is quite a bit of flexing between the frame & the body of the vehicle while driving down the road. Just look under the hood of a newer vehicle with a "Split" master & you will see what I'm talking about. You can make the curls/coils by twisting it around a approx. 1" socket.
Tom T.
You should check NOW to see if ALL the bleeder screws on each indivdual wheel cylinder are free before you even start on the conversion to try & save you some time & get the nec. wheel cylinders beforehand.
