Um, there's a little bit of unresolved ambiguity here, much of it due to Folmer & Schwing's (and successors') confusing naming conventions.
OP, when you write "Graflex" do you mean Graflex SLR with Graflex back (one slider, raised ridge at the insertion end of the back) or Graphic (press camera)? If you mean press camera, do you mean press camera with Graphic (also called spring) back, Graflex (see above) back, or Graflok back (two sliders, slot towards the insertion end of the back). With one exception, roll holders that will attach to a Graflex back can't be attached to a Graflok back and vice versa. The exception, quite uncommon, is a '"23" Graflex' holder that will attach to both types. Graphic (spring) backs don't allow easy use of the roll holders Graflex made. Two solutions: for 2x3, 3x4, and 4x5 Graphic backs the appropriate size of Adapt-A-Roll 620, for 4x5 the Calumet C2 or C2N. Busch made a slip-in roll holder that took 120 film for the 2x3 Pressman, which has a spring back; these are very rare, as in if you want one you won't be able to find one.
Versions of these cameras were made with gates 2.25" x 3.25" (2x3), 3.25" x 4.25" (3x4), 4" x 5" (4x5), and 5" x 7" (5x7). Roll holders that accept 120 film were made for 2x3, 3x4, and 4x5 Graflex made cameras with Graflok (usually press cameras) and Graflex (usually SLRs) backs. All have the same carriers, for formats larger than 2x3 the shells are on mounting plates to fit the camera.
Graphic 23 roll holders accept 120 film, shoot 8 frames sized approximately 2.25" x 3.25". Graphic 22 roll holders accept 120 film, shoot 12 frames sized approximately 2.25" x 2.25". All have carriers with knob wind, most have shells without pin rollers at the ends of the gate.
These were replaced by RH-8 (replaces the 23), RH-10 (new idea, 10 2.25" x 2.75" frames), and RH-12 (replaces the 22). Carriers with lever wind, shells with pin rollers at the ends of the gate. Ain't no RH-6. There's also an RH-50 that shoots 2x3 on 70 mm film, fits, IIRC, only the Graflex XL.
Masks? Graflex sold finder masks to suit the lens' focal length and the roll holder's gate. There's a table, mask # given focal length and format, in the RH user's manual, may be posted on www.graflex.org, to which you've already been directed, and on www.southbristolviews.com. Look both places.
I use a Graflex 2x3 camera as my main film camera. I have the "23" 120 back which takes 8 6x9's on a 120 roll as well as the (5?) sheet cut film holder.
I use it like a view camera and take off the GG and slide the 120 back on.
Works great for me!
Canon EOS Elan II/E, Elan 7, and 630. -- Bronica ETRS -- Pentax 6x7