Thanks, AgX - it answered some of my questions - very good!
I was thinking of the inner diameter of the reels, if it is the same throughout the versions - I wasn't clear enough in my original post about that.
It struck me while loading the 1000 reels that they operated differently compared to the Paterson ball bearing ones, but it was easy to adjust my modus operandi.
Improvisation, indeed! I was a bit worried fumbling about in the darkroom bag for a while, but as any stalwart explorer I adjusted to the circumstances. I think mine are the more advanced two-recess version.