Bump and update:
Taking off the entire drum assembly ended up being very easy. 4 13mm bolts that are big enough that a little rust didn't do them in, unhook the ebrake cable that had rust welded itself to the connector, and cut the hard lines. So off they went. The 8mm M6 bolts holding the drum cylinders were not so lucky. On each side one came off and the other started rounding, so I will just wait until the bolt extractor comes in.

Pic related: the two bolts on the bottom of the assembly are holding the cylinder in place. The green one is me determining what size bolt I needed. Wire brushing revealed where the bleeder screw originally was, but it's just gone.