Hi Again Robert,
Yes increasing the diameter of the modern 120 spools which results in beautiful even frame spacing, as you can see.
I used three go-rounds of duct tape on each spool and it does the job (sort of). See below.
DSC05861 (2) by
Nokton48, on Flickr
DSC05851 by
Nokton48, on Flickr
The Makina "advancing key" fits tightly and precisely in the wooden slotted end of the spool. Just exactly like it was made for it!
Kodak 120 film spools by
Nokton48, on Flickr
However, the tape is not wide enough, and can result in uneven roll winding. The result is straining to get the film through the film back all the way to the end of the roll, not a good thing for it's gearing, etc.
These old wooden spools are the answer. Easy to load (no taping of the roll when loading, a real pain!) and it really goes through smoothly. I have some Kodak, Agfa, and unmarked spools, they are all identical except for the metal stamping.
Try one and be amazed! These are the right take up spools for these really old film backs.