You mention gas flowing from the carb, was this before or after trying to start the engine ?
Once the carb is empty it will not fill again until vacuum is applied to the cutoff valve under the gas tank (disconnect the vacuum tube from the intake manifold and suck on it so the valve clicks open, there's also a drain screw on the carb that you can use to check if there's any gas in the carb)
If the float chamber of the carb seems full of gas and still nothing gets into the engine I would check first if the main jet is clogged. Other possibilities could be that the float level is extremely low, or the needle or vacuum piston is not fitted correctly in such a way that the needle shuts off the needle jet completely.
Carbs can be tricky...