Donald Qualls
Subscriber
I can pick up the developer alternative to Adotech IV hunt, after I get a few other projects out of the way!
Or you can use a Caffenol variant -- Caffenol LC+C, which I've used in the past for Imagelink and Copex Rapid microfilm stocks (and old CMS 20, around 2006).
Usually the masks are for 6x6 with a 6x9 folding camera. Sometimes these are two flaps that fold away for 6x9, and out across the film gate for 6x6.
Ian
If the two windows are in line on the bottom (or top, depending on winding knob/key location), any mask would be for 6x4.5. If one is in a corner of the back and the other in the center, it'd be a 6x6 mask.