I'm not sure what theory those umbrella seals theoretically operate under, but I can't really see how they meaningfully keep oil out of the guides, on the other side of the spring retainer and 1/2 inch down the valve stem.

But smoking on idling is probably a little oil coming down past those guides. There's a lot of vacuum in the intake ports at idle, that really works hard at getting oil to suck down past the guides into the intake.

As for the idle sticking, it's very likely the carb hanging open slightly. There's really nothing else that's going to give you the same symptoms. One of the throttle valves is probably binding up on something (perhaps the carb throat) and failing to close completely. Could be a loose disc as mentioned, could also just be very slightly misaligned.

Might check for a little slack in the throttle shafts, not sure if the rebuild included rebushing those or not. With a little slack it gives the throttle plate ample opportunity to move around a little and bind up before closing.
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'63 PV544 rat rod, '93 Classic #1141 245 (now w/16V turbo)