One more bit on the subject: going through my parts drawer, I found these wire crimp (or shrink?) connectors to fit both the large camera pins and the standard 120 spool recesses:
The ones I tried were same ^^ pink, a size code, I think.
Cut in halves, press in spool. Near friction-free spool rotation, proper centering.
Obviously does not work with the take up, no drive wings.
(Note: there seem to be a gazillion wire connectors in the diameter range of interest!)
I have some success over-drilling my Holgamod spacers described early on, allowing more of the pins going in.
So, if it works, I could then have a 120 as take up.. which means I could send out color 120s!