I made an quick experiment and found , for each spool cavity , one 35 mm cassette fits perfectly. There is only need a 35 mm cassette buttom and up supports and cutting single spool to be placed top of the cassete between winder gear and cassette gear. I am sorry to not make this experiment earlier. Winder turning ratio can be determined by an developed film in these cassettes and place a mark with graphite pencil on to winder knob and the camera.
No need to worry about light leak because everything protected.
35mm cassettes are fitting to the cavities perfectly without moving.
I photograph our garden and close distance subjects plus morning light hit balcony or rainy night traffic and my taste for bw is champagne grade with beer wallet. I think snow would be an good subject for bw but there are two months to this weathers photographs.
24x60 will be funny.