Using the Ansco Readyflash Part1: Spooling 620 Film
There are a lot of sites with instructions for paring down 120 spools instead of re-spooling. Give it a whirl if you don’t mind risking a roll. A couple of examples:
One warning if you decide to go this route: The 620 film slot and the corresponding piece in the camera that turns it are smaller. Make sure the adapted roll is smooth on the ends and rotates freely. Otherwise, the bit inside the camera may rotate inside the slot of the film spool and break it. Filing the end of the spool makes it even weaker. See my experience using a 120 spool in a Rover (Diana) camera.
Using the Ansco Readyflash Part2: Loading & Shooting
Film Photography Project 620 film goodies: https://filmphotographystore.com/collections/all/620-film