Use a vacuum pump and check all choke pull offs. Make sure the choke opens when warm. As previously mentioned put the vehicle on jack stands. Use a flashlight and look over the fuel tank and follow the gas line to the carburetor. Fuel pumps also will leak when going bad.
Carburetor cleaner isn't as good as it used to be boil in an old pan after dismantled with plastic or rubber parts removed. Use a rolling boil for 20 minutes.
Put the float in your hand and shake if you feel liquid replace with a new one.
Napa should carry all parts needed.