Thanks, Mike. I hope others will benefit from these, too.
As I suspected, it sounds really smooove.
One telltale I listen for when dialing in the carbs is the sound just off idle - when the throttles are just starting to open. If it's out of synch at all, you will hear it there. Yours is dead smooth, side to side.
And it sounds really strong accelerating under load, too.
One sound I think is common to all of these engines, though - that faint 'too fast' when you're into it just right.