There are three issues that I think of that make a difference.

First is the size of the bore. If both bores are the same size its a non-issue but if they happen to be different sizes you need to match them correctly to front and rear.

Second is reservoir size. Disk brakes require more fluid displacement and therefore usually require a larger reservoir. In a front disk/rear drum application that would make a difference.

Third is the possible presence of internal residual pressure valves. When needed disk brakes need a 2 pound valve and drum brakes need a 10 pound. If your master has built in residual valves they need to match your brakes.

While you describe your project as drum brakes if you are using a newer master it was probably designed for a disk/disk or disk/drum system and some of these issues could impact your project.

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...