An easy solution is to use a Du-Bro fuel valve. It uses 2 lines. The fuel supply line is disconnected while fueling so the engine doesn't flood. The overflow goes to the muffler which should be disconnected to avoid filling the muffler with fuel.

2 line set up:
One line from the clunk to the engine. A filter can be used before the carb to keep it clean. Over-flow line to the muffler. (Fill the tank from behind the filter if one is used).

3 line set up:
Same as 2 line except the 3rd line if used for over flow. It must be blocked so the engine will get muffler pressure. (I don't use or recommend this).

EXCAP232