I love it when it's something obvious!!
Just got back from the carb guys shop. Pulled the float bowl on #1 and found the slow jet loose and hung up around the float.
He still has all the original jets and will clean and inspect them and re-use them if they pass muster. The O-rings in this kit are already showing signs of getting soft and goopy, too. He has an assortment of the proper fuel resistant O-rings and will replace them as well.
He's going to re-check the float height, bench synch and check the springs in the linkage holder arms. He soda blasted the carbs and wants to make sure there's nothing in there that would be keeping the RPM's from dropping back.
I'm pretty sure it's ALL related to the lack of slow jetting in the carb.