quick update, split the bike this afternoon to give it a good clean and put back together. Probably didn't really need it, but I prefer to know it's been built correctly. All came apart as if it was built last week and not 15 years ago or more, so that was a nice surprise. I've measured the seatpost at 29.0mm.
Looking for info on the ITM Millenium Wing Shape carbon bars. The sound of them, thinness of the tube walls at the ends, and a scratch test at one end have confirmed that they are alloy with a carbon wrap in the centre, so I will probably try them and see how I go. I have a set of alloy 3T belgian drop bars I could use instead though.
Also, how many cage lengths were the chorus 10 speed rear mechs available in? This one is definitely longer than "short cage", I am guessing only two options, but maybe there were more? Strange to see it on this build, as cranks are standard 135mm BCD and the largest sprocket is either a 23 or 25 (didn't count or look for the number, but it's not a 29, at most a 27, so there would be no need for the long cage mech.