Welcome to the Club!!!
Reading your post, I understand this:
1. Ran good some time ago.
2. Performed carb rework.
3. Now it doesn't work like it used to, correct?
At any rate, my suggestions are to remove sight plugs and reset fuel level, especially front bowl.
Very good symptom given: "...fuel on the secondary throttle plates..." But, you further say after its been sitting a while. If sitting period is within the same day, I would think its fuel coming out the front bowl vent tube and splashing onto the plates during takeoff. That's why I suggested to reset float level, maybe even alittle lower than the sight plug. If it after several days, don't have a clue. Fuel would have evaporated within 24 hours.
If the float level doesn't get it, you might install a Vent Baffle, Holley P/N 26-40, into the front metering block.
I would think alittle more initial timing would help also, i.e., 12-16*.