Now I know why 904 was having issues

You can get a new drum and band and they are not too expensive at all.
If I were you I would at least do a clutch frictions, bands and soft parts rebuild if you don't find anything else worn real bad.
I looks like the endplay was a little excessive from the looks of those ring land grooves.

How do the pump gears look?

For sure pull the servo like AJ mentioned and make sure it's not destroyed in there, because if it is you'll be looking for another transmission core or case to rebuild.
Might do this early on to make sure the case isn't unusable.