The '66 G80CS on/off road model which I had used an Amal Monobloc (1-3/16"?) and I think the G85CS would have had an Amal GP carb.
Thanks for that info Knut.
I've read that there were a few TCS built from 59 on, not sure if that is correct.
This TCS owner says the early bikes had a slightly smaller bore.