Sorry for the very late reply. My camera is not a Maximar, but a Welta (German camera) from 1922. It has a Doppel Anastigmat Eurynar 1:3.5 f=13.5cm lens. It has a ground glass back (that can be removed) and some of the original sheet film holders (metal, one sided). It is in new condition and the shutters fires correctly at all speeds. I only need to replace the suede/velvet light seal on the back.
I do have a roll film back, but I'm not sure if it fits this camera. Never tried, but would be a nice addition to this camera.
I'll try to match it: thanks for the idea!!