Sounds like a good plan.
Might as well remove the master when you can and see if it just needs new seals or if there is bore issues.
If you get stuck I've got a bolt down top master here - supposedly good when it was given to me, and a bail top that I know leaks but haven't examined to see why.
Drum braking systems have their quirks but they can work quite well...even if you run it at Atco or autocross it at Bader. The 10" drums that came with a 318 are decently sized.