Be careful removing the idle limiter caps, on some designs the idle screws underneath are made to break off easily doing it as you are messing with emissions settings. Open the screw up some as removing the caps tends to put side force on the screw, you don't want that anywhere near the seat when it happens.
I forget these use a positive linkage setup instead of individual cables, in that case any sync linkage or screw is the same thing as adjusting a cable. Usually one carb is chosen to be the 'base or master' and non-adjustable, the other(s) then set to match it.
If you guys are talking a single position manometer then you are setting to pure idle only and only part of the work. You are only doing a half sync like that, complete has you barely opening the throttle to check the drop off matching of both (or all) cylinders as you just crack the throttle and you think both are even at idle but they both can then act different at pullaway. The difference if there can say more than one thing and you can't tell that without two gauges on a twin and even then they need to be a matched set. Why I never use gauges on a 4, too hard to get 4 of them at the same setting, far easier to use the tube type that has all cylinders pull off the same medium to be perfectly matched so there is no question as to the action of each cylinder. If you pay attention you can even pick up on say one cylinder being slightly weaker than the other to then match them a bit cockeyed at the dropoff to then idle smoother and give a better pullaway too. When engines get older the cylinders have different demands on the carbs at idle and off-idle and you can fix some of that to not be as irregular as it normally would be. Simply getting the curb idle vacuum the same will not do any of that.
Of course, yours and do what you will.