Will a 71/72 booster work on a 70 drum brake trk?

[Longhorn 70]

I am also told that the residule pressure helps keep wheel cylinders from collapsing and mantains the proper activating rod/piston distance.

The master cylinders I have seen for disc are also bigger diameter bore than drum only. They also have a small dimple in the main piston rather than the deep dimple for drum masters.

This indicates as long as you are using the drum master and booster as a set or the disc master / booster you'll be OK but not optimum. The disc setup may have problems with the front brakes not coming on fast enough due to lack of residule pressure.

Then there is the proportioning valve vs. distribution block issue.