I looked at mine again and dug out the cheap Shyneese caliper. It is 11.600" vs the 11-3/4" I got with the Craftsman 20' depth indicator (Lol, tape).
I don't see any reason the OD on these drums couldn't be machined down if you have the ability. There's no lip on them anyway. My old stock drum is 11-1/2" over the OD of the outer lip.