I have found an interesting diagram when I was looking for ideas about how to run S4 parts in the brake system (already have them) of the 78. I occasionally think that I want ABS in the car, but that would prove very complex, and this shows a very easy way to use the S4 booster and master with the proper line routing using exist parts, and not falling into the trap of having the wrong piston size in the master:

 

And I may paint them red.