http://vintage-and-classic-hondas.81.s1.nabble.com/Engine-High-Idle-tp4040909p4042722.html
Those rings being upped around might have been the issue that caused your high idle.
Am i seeing Allen head screws everywhere? Those aren't stock and are a common upgrade, so it looks like a Po at least tried to take care of those carbs.
Why did you need to cut into those choke plate screws? Was the Allen head stripped?
Current Status June 21:
Removed all the carburetors. Inspected all the boots. Look good. Ordered new o-rings for the fuel connecting tubes. I had to cut a slot in all the choke plate screw heads to remove them. Ordered new screws. Disassembled the carburetor pistons. Discovered some gaulling on the surfaces. Removed using 1000 grit paper and polished using a dremmel. Discovered the large seals were not installed consistent. Some had lip facing up and some down. Installed all seals so the lip side laid against the carb housing. Awaiting receipt of the o-rings and screws before I can reassemble and try.
Took the extra time to do some cleaning and polishing of the carbs. I bought a new Dremmel and really love it.
Removing the choke plates



1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals
My wife's recipe website that I'm trying to help promote:
Strawberries for supper. Yes, I am a lucky man.