I’ve never really had much trouble with getting a steady idle unless the inlet rubbers are split, but I can’t imagine Micheal running a bike with split rubbers! My current bike starts easily on choke which I turn fully off as soon as I’m on the road. After 2 miles or so it idles comfortably at 800rpm although if I’m gentle it will tick over at 600.
Apart from balancing the carbs properly (they don’t look balanced to me in that pic above) it pays to set the air screw according to the manual, also, of course, the ignition timing!
Also when you reassemble the carbs, rub the CV bores with wire wool then wipe with light oil so the return spring can push the slides down easily, since it’s a lot weaker than the vacuum pulling them up. There might be a ledge of old fuel left that stops them dropping fully as well.