The high and low needles have nothing to do with the fuel draw of a gasser carb..Fuel gets into the engine AFTER it gets drawn into the chamber under the diaphragm that operates the needle..
You can't blow into the fuel inlet and unseat the needle if it's working properly...
A gasser carb WILL draw fuel 4 feet straight up if it gets a pulse from the crankcase...
Any leak that keeps the pulse from getting to the carb will keep it from working...