Ok,
Just finished balancing the Interstate using the Digi Sync.
Went about things a little differently than normal.
Put the bike on the lift, removed all the required parts.
Pulled the spark plug boots on all cylinders once the engine was cold so as to have room for my fat fingers.
Installed the long hoses to the Digi Sync (Q-Tip with just a touch of vaseline on the end of the hose
lets these glide into place).
I routed the hoses between the carb structure so they came to the port from above and behind, and used one of those 4 fingered flexible pick up tools to set the hoses onto the ports. this is really the cats behind for making the job easy.
Replaced the spark plug boots.
Fired the engine, put a fan in front of the radiator, and let things get warm.
From the looks of the existing port boots I doubt they had ever been removed so the carbs were as out of sync as I suspected.
Getting things lined up took about 5-7 minutes until everything was +/- 1 on the scale against carb 3. Checked at 3k rpm, even bettererer.

Letting things cool at the moment so I'll remove the hoses, re-install all the hard parts removed for the procedure and go enjoy an evening ride on a much more responsive beast.
Having used carb stick in previous years, I could kick myself for procrastinating about buying this tool. It's fantastic.