refill radiator and overflow tank and monitor it for a couple of days. if it stays full of coolant it should not overheat any. look for a green drip at the bottom of the water pump every time you shut it off and a slow and steady loss of fluid.
what will sometimes happen is that it won't lead during operation, but will leak heavily after the engine is shut off, when the heat and pressure builds up. once cool, it might stop dripping.
depending on mileage, money, time etc, you might replace water pump only, or take the opportunity to strip the motor and also fix the plenum and replace timing chain and seals and any other oil leaks you might have.