What is the difference between a power brake master and a manual brake master cylinder?
As a general rule, a power brake master cylinder will have a larger bore diameter than a manual brake master. A manual master will also usually have a deep piston hole to accept the manual brake push rod while a power brake master will normally have a shallow hole.
These people offer good tutelage on braking systems-
Also consider early drum applications used differing size wheel cylinders/brake lines for proper brake balance before valving became popular.