Sounds plausable. If the rods are not getting pulled down quickly enough, excess fuel will drip into the venturi. I'd also check to insure the rod plungers move freely. I had a problem with one that didn't, and it dribbled fuel constantly into one venturi.
As for not returning to idle quickly enough, that could be from a vacuum leak, or weak return spring/binding linkage.

Could be binding linkage. I recall I snugged it, perhaps too snug.

I suspected a vacuum leak too but I made sure the new brake hose was secure. Maybe it's the carb gasket. It's old so I should just swap it out to eliminate it. Thanks.

I had some success today. The way I attatched the cable to the carb linkage was with two pieces of steel with a hole at each end 1" apart. I secured them to the carb with a small bolt and two nuts counter-tightened to allow slack in the linkage and not come loose. It works well. I had the nuts a little too tight so that's fixed now.

The other weird part that I haven't figured out yet is that the carb linkage is actually getting stuck internally. It slows the return to idle and makes the gas pedal stiff at first. Is there any place I should lube? Maybe run premix? Or plumb the OMP into the carb float bowl like a Holley?

My cable is hooked in a similar manner. 2 ~1/4" X 1.5" strips of metal, with 3 holes. One end has holes big enough for the cable end, and the other 2 are just big enough for a screw to fit thru. The center screw holds everything together, and the end screw attaches it to the linkage. Lock nuts are used on both. The screws are only snugged enough to keep the cable from falling out, and allows for free movement at the carb.

As for the linkage binding, perhaps the AP linkage is in a bind, or the primary-secondary linkage at the other side is interfering with the water outlet or binding. Other than those 2 spots, only place I could imagine any binding, would either be inside the AP, or the throttle shaft itself. I mean, these are very simple (but effective) carbs.