Nigel, well done and it is very satisfying to get carburation right, because it can be a bear. I remember from previous posts that you have Premiers, although I haven't trawled through to see if they were they were sent jetted specifically for the T120.
I am going to try making cable elbows for the carbs on mine, or adapt some to fit. That would resolve the cable routing under the tank, which is also an annoying detail on Commandos. Why on earth did they not make elbows? Triumph did make a throttle cable with an elbow for the early Bonnies, but at the twist grip (for those flattish bars). It would not have taken much to do the same at the other end. I thought they were pretty thorough with most other fittings and fixtures on the 60s bikes.