Thank you. I think this is, indeed, an option for me, Disraeli Gears says that this derailleur was built until 1949, too, so would be both place- and period-correct.

This is the one I own, and will give it a try as soon as I purchase some half nuts and star washers: https://www.disraeligears.co.uk/site...ns_scan_3.html

The problem I might face is getting spring #1625 to compress enough to get to the smallest sprocket.
I'll post again when I have it set up.