Seems to me you might want to take a look at the fender tag and see how much info is on it. Shop manual will have some basic decoding. Some of the guys here will be helpful, especially if you are putting some effort in on your end. In addition to the imperial club, another great resource is
The 1970 Hamtramck Registry Home Page
List of master tech bulletins and filmstrips:
Master Technician Service Conference - Chrysler's Training for Mechanics
here's direct to a picture of the combo valve:
1970 Chrysler Imperial Hydraulic Brake Service Guide from the Master Technicians Service Conference Session 274
1970 gets confusing with all the variations, even though the concepts remain the same. That's why I didn't want to post that earlier when it seemed likely the disks were a factory option.