I have a 220 back that I'd like to shoot 120 film in. Will the differences in the pressure plate, or anything else, cause problems with 120 film installed? Can I modify it somehow? I don't really know much about these backs (I don't own an RB); I bought it from a buddy when I dropped it and cracked it. I'd like to use it to construct a pinhole cam and/or a roll back for a home built 4x5, but 220 film isn't very readily available.