69 340 AVS fuel leak

You may not be seeing the perculating or running over as you say while the engine is running because of the draw of fuel through the venturi's. Also, as RedFish said depending on which kit you have, many of the zip kits listed many different float settings for different 340 carbs based on manual trans or auto trans. I still have and original carb kit spec sheet at home along with the 69 Chrysler repair manual with the right specs in it. I'll check it out when I get home from work and get back to you. Remember that when the float levels are being set, it is necessary to invert the air horn and take the measurment form the far end of the float away from the seat end and measure from the gasket to the float. I'm sure your guy did this as it shows in the instruction sheet, but just thought I'd mention it.