Or…. Use your dial caliper to measure the distance between the mating surfaces and the mechanical interfaces, and draw up a diagram.
Then adjust the pushrod length to get close to the required gap (for example, shoot for .20”). Again, use the dial caliper to tweak your adjustment, and verify the measurement…
Then assemble the master/booster combo with a blob of clay on the end of the pushrod.
Then disassemble. The thickness of the clay shows your free play. Of course, tighten the mounting bolts fully when you are “mocking it up”…
Adjust to final specifications… reassemble…
Rocky