So as @Captain Obvious says, when I took apart thee set of worn carbs that I’m modifying (eventually!!) I found that worn “collar” was 9.5mm and the wear on the bush was about 0.4mm.
The wear on both ends was 180° with 90° being the most worn but interestingly the wear was 90° offset rotational from one end to the other!
The chap in Birmingham (UK) is remaking new shafts. I can only assume Ztherapy do the same.
Butterflies don’t really wear appreciably. But I’m happy to be corrected.
I’m potentially going to get a buddy to CNC some new stainless steel shafts for me, but they will be “modified for flow versions”, not stock.
Happy to measure / share stock dimensions if any good to anyone wishing to CAD them and make some..