340 not running anymore...Help Please?

The rebuild kits fit a number of different carbs so you will have a bunch of parts left over.

One thing to double check is the gasket that goes between the metering block and the main body of the carb on the primary side. Some of the kits have two different ones and the difference is subtle. About one third of the way down from the top of the gasket and centered left/right will either be a hole or a rounded notch. If you use the wrong one fuel will leak directly into the main body well and will flow over every where. Most of the newer carbs use the one with a hole.