Try the simple fixes first- - - -lower the float level a little and do a test drive. Also look for imperfections in the carb casting that might allow gas to escape between the main casting and the top from splash. It only takes a few drops of spillage onto the manifold to create a strong odor, and by the time you get the hood open and look for wet spots there might not be any to see. Also, look for clean spots around the fuel pump area- - - -I've seen gas squirting from a leaky pump casting, even on brand new pumps, but only at speeds above idle.
Jerry