i found your other thread .. says it's leaking from the tube at the bottom of the bowl.
As noted, this is probably one of the overflows .. a thin, vertical metal tube in the float bowl is attached to the drain. When fuel rises above the tube's top end, fuel goes into it, down and out the drain hose.
another "overflow" would be at the top of the carb.. it's just a hole. This hole is actually a vent hole, but sometimes fuel rises so fast and so high it also comes out of this vent.
Testing the needle for a leak is not easy .. but not too hard.
Turn off the tank petcock. Remove the carb
Get a wide clear glass .. wide enough to set the carb in it.
Remove the carb float bowl.. let the float hang in mid air..
Hold the carb level, and lower the carb into the glass. Hold it above the bottom so the float hangs freely, and turn on the tank fuel petcock. Fuel will flow through the needle valve and into the glass.
Hold the carb steady as the glass fills with fuel.
At some point the float will float upwards and rise and push the needle upwards. Fuel flow into the glass should stop when the float rises nearly level with the carburetor's bottom. If fuel does not stop the needle is leaking.
try removing the carb from the glass and push up very gently on the float. This also closes the needle against it's seat. It should stop fuel from flowing.. If it doesn't that needle is certainly leaking.. It or it's seat is worn or dirty or damaged.
A new needle is usually all it takes to fix this type of leak. Sometimes the needle seat is damaged but it's rarer. The seat can be smoothed out with the correct little cutting tool. However this is tricky and shouldn't be attempted if you're not sure about what you're doing.