As the others said, check the float level and that it doesn't have a hole in it. If you are contemplating changing the carburetor, then don't install a Weber. They are finicky and often expensive. A Holley 350 and adapter plate will be easier and probably a whole loit cheaper. But the smartest move would be to take it to someone who knows about carbys and have them fix it properly. Carbs are generally easy if you are careful. Don't change it until you are out of options.