You'll be glad you ordered the Uni-Syn.
You might move the throttles to make the accel. pumps squirt a little gas in each carb before messing with the adjustments. It wouldn't hurt to connect the linkage so you can use the throttle/pedal to get it going and warmed up. Once warmed up you'll be able to better gauge what you need to do with the screws.
If it's obviously not getting enough gas for idle and you can't get it to run on its own go ahead and turn in the idle speed screws to increase speed, and maybe go ahead and open up the mixture screws a little if it's still struggling to get gas. Be sure to make the same adjustment to both carbs - whatever you do to one do to the other. You might have to play around with them for a bit before getting it to idle. Let your intuition guide you on which screws to turn, idle speed or mixture, in or out.
Once you get it to idle reasonably on its own fully warmed up disconnect the linkage and then do the carb fine tuning with your new Uni-Syn. At this point it shouldn't take too much fiddling with the screws to get them balanced. You may need to make adjustments to one carb without touching the other, and that's OK so long as you're not making a "gross" adjustment of either speed or mixture. It's all a balancing act, and again, let your intuition guide you.
Once you've got them balanced at idle go back to the linkage and make whatever small adjustments you need to compensate for any minor differences between the carbs you had to make and you should be set.
And once you've come this far it wouldn't hurt to think about using your Uni-Syn to check balance at higher RPMs, and possibly fine tuning your linkage some more. You can adjust the Uni-Syn's sensitivity range to get readings at higher air flow rates. If you find that one carb begins pulling more at mid and high RPMs then you can think about making adjustments to the small push-rods between the relay and throttle levers to compensate. This is where you might end up making the small rods slightly different lengths to dial in carb balance at various throttle positions.
Have fun!
