Rechecked points, verified timing, and even lowered the float to a point I know is a tad too low. Car runs alright down the road but is still burning way too rich, particularly at idle; vacuum port at the base of the carb is clear. I tried both advancing and retarding the timing a touch just to see what happened, and the car didn't like being anywhere but 0 degrees TDC at idle.
Haven't found a way to properly vacuum test the carb, and the car doesn't have vacuum wipers. This has to be something to do with the carburetor, which baffles me considering it's been rebuilt and cleaned to a T several times over the past year. As I posted earlier, I haven't taken out the main vent tube and I'm still thinking this could be a part of my issue. I don't have the tool and it isn't easy to come by. Only place that I can find it is open Mondays and Tuesdays and that's it. Other than that I guess maybe I've got too high of fuel pressure coming through the rebuilt pump. Not being able to kill the car by seating the idle mixture screw at idle tells me it's in the carb.