I saw the job Chris did on WN's roadster. Surprising how straight forward the replacement is and the appearance is so much like the 11" Model A that they are nearly undetectable.
The drums are so common because they have no use in a hydraulic conversion. Narrower shoes than the '35 on, they can be very cheap. When a '32 restoring friend bought a brake lathe, I bought many for his practice. Because I always carry brake mike, the friend has the best that is out there.
Good Luck: Fred A