After recently acquiring quite a lot of aerial roll film of 9.5", 5", and 70mm widths, I wondered how to shoot the stuff in my 11x14".
You could of course make a modified back and holders etc, but a much simpler and less costly solution occurred to me: a simple paper sleeve. This is illustrated in the attached cellphone pictures. It works very well and costs almost nothing.
What you do is get some black construction paper from a craft store and fold it such that you create a kind of sleeve to slide the film into. You can do this quite easily by first cutting a piece of film and then folding the paper around it, creasing it as tightly as you can. The hardest part is centering the sleeve properly; if you're more patient than I, you will diligently measure things and then transfer the image area properly to your ground glass for more accurate composition
One of the attached images shows a side view of the folds that you'll need to secure your roll film properly, while covering only the edges.
Important: it seems best to insert the roll film into the holder such that its natural curve is along the long axis of the holder. That way, the curviness of the film tends to secure it in place and it doesn't buckle in the middle. E.g. in the case of the 9.5" roll film, the image size in an 11x14" holder is roughly 9" by 14". Quite a nice aspect ratio
This method should work well for any roll film inserted into any sheet film holder. I think it'd work for putting 120/220 or 70mm film into a 4x10 holder, and so forth.
Be creative and enjoy