Hi Keith
I wouldn't disagree with your list of difficulties setting up twin SU's. But I think you've over dramatised them somewhat. When I was a whippersnapper I would have accepted the burnt fingers from swapping hot plugs around. Today, I simply use a second colourtune! I get on pretty well with a piece of pipe to the ear. I use a pice of heater air duct tube around 2" diameter. I've not tried this on a 2000TC, but I wouldn't be surprised to be caught out by the low air velocities at idle. This is not so much a challenge to set up technique but a condemnation of Rover's carb selection. It's now firmly established that the 2000TC benefits hugely from binning the existing set up and substituting the twin HIF6's (or is it HIF44's -can never rememmber!) from the 2200TC.
I note your comments about setting up the linkages. I find that you are better off to do your own thing based on an understanding of what is trying to be achieved rather than the workshop manual's specific method of doing so. HArvey and I have a disagreement running on this. HArvey likes to set the carbs up with the interlink disconnected and then resonnect the llink to suit. I prefer to set the link to give an acceptable compromise between both carbs reaching full throttle together and both carbs shutting off fully together. I skew my settings to the full throttle being correct. This takes care of balance at high rpm, I then set low rpm mixture and balance from the idle adjustment.
But of course all that assumes the carbs are working correctly. And there are two key settings that must be checked first. These are the petrol level in the float chambers being exactly the same in both carbs and the fall time of the pistons from the dashpots being identical. For the latter it is necessary to clean out all varnish and dirt from the inner surfaces of both, then test the fall times minus the springs. I see no issues in swapping pistons and dashpots around until you have a matched pair - after all, that's only what the factory supposedly did. Then match the free length of the springs and you have a matched pair of carbs. The matching is far more important than getting the fall time precisely spot on. You can correct for that later by needle selection if really fussed.
I'm intrigued by your comment about inequality between cylinders on the 2000TC. I suspect that could be an effect of the very low gas velocity amplifying any minor errors in the passages etc. I suspect it might sort itself out at higher revs. It would be interesting to see if the smaller carbs correct this - implying that it is the carbs at fault - or whether there is no difference implying that it is the head porting.
Chris