[Bob Putnam]

5 psi is probably a bit much for the Weber floats. Why not just run a return line with a restrictor back to the tank? All you need is a 1/16" hole to return excess pressure but not bleed off so much that you starve the engine.

Just as an experiment to check whether your standard float levels are causing this, I would run the car, shut it off, and then bleed off pressure at the pump. Then check if you're still getting the fuel drip.