I just picked up a french 6 x 9 box camera that is missing the red window from the back that shows the frame number. Any ideas on what I could use to put in the hole and still read the numbers not letting light in. It takes 620 film but I hope to try it with 120 with a couple of mods. Not sure if the film numbering on 120 will match with the frame indicator window though.

Also, I have a six 16 brownie that takes 616 film. Can this be modified to take 120 film? Or, is it better to make it a display piece?