You're doing well.
Yes, the correct master cylinder will be for a front disc/rear drum system.
There will be other safety related things you may wish to do that we can help you with.
The first one is an electrical safety upgrade, and it is to bypass how the electrical gets from the battery to your ampere gauge on the dash and back out to the dash. The conndctors arrangement is a poor design that does not age well, and poses a fire risk.
You can also improve your headlight system both for its electrical safety and the performance of the system with relays and as part of the bypass noted above.
You need to have a mechanic check the rubber steering column coupler - it can degrade and need replacing, or it can fail. Parts are available.
We can help.