spleenrippa, if you have a rangefinder on that old camera then the focus panel can be removed, a roll film holder installed in its place. A focus scale can be used also if a rangefinder is not available. 3x4 roll film holders show up occasionally. An adapter can be made to reduce the 3x4 format to 2x3 format but any focus scale or rangefinder will have to be reset. Roll film holders for 2x3 format cameras are readily available.
hensman, See http://www.graflex.org/helpboard/viewtopic.php?t=6391 . Film flatness issues will come into play if doing extreme closeup/macro or critical architecture work. Flatness and spacing issues are a result of modern film being .5mm to 1mm thinner than older film. 120 format has been around since the early 1900's.
The shell for a given format has a film gate opening for that format. A shell for 6x9 can be used for 6x7 and 6x6 provided that inserts for those formats that fit the shell are available and a format reducer is installed in the film gate opening. A simple format reducer can be made of thin metal and inserted into the darkslide slot.
220 film has backing paper at the lead and trail end only. The pressure plate on a 220 insert is closer to the film shell by .006 inch which may cause focus issues when shooting fast lens wide open and increased tension on the winding mechanism if using 120 film.