I'll presume you have the later carbs with the linked arm throttle assembly, I think the 4-cable ones were only K0 but not sure.
Check the choke throttle advance cam. There should be an adjuster screw in the mechanism, it can set a false minimum idle. One way to check is to activate the choke a tiny bit, the idle speed should not change for a small choke setting as the "slack" in that idle advance mechanism takes up. If your idle rises with even a miniscule choke setting then I'd have a good look for the adjustment.
The jetting sets the idle mixture, not RPM. You want the 4 carb idle mixtures set for the highest RPM idle you can get and then set the actual idle RPM with the idle speed knob.