Blue Moon, who advertise on APUG have a nice variety of films that they modify to fit 620 cameras.
The prices are quite reasonable, but there is another alternative. Years ago, I made a 'film sharpener'
with four bits of wood, glue, screws, and two of those blades that come on a nice pencil sharpener.
Glue two flat pieces along their lengths in a right angle, add two triangles appropriately apart, and
fasten on the blades. Push the roll into position, and roll to shave. If you haven't a caliper or
appropriate wrench, make a gauge .
I sold mine to a student, but he moved away, and I still have my Medalist I !