I agree that a lean condition can be deadly and can cause overheating. I would correct that as a first order of business. Fatten it up a couple jet sizes at least. Another thing to check is your lower radiator hose. If it is old and worn, it can collapse under suction from the engine and block or reduce coolant flow. With the engine cool, reach down and squeeze the lower hose, if it can be compressed easily, replace it with a new one. Let us know what you figure out.

Pat