Just my two cents worth, but I would remove the spark plugs, ensure radiator is full and beg,steal or borrow a cooling system pressure tester.Pump it up to what ever your cap pressure is and leave it sit a couple of days,water should appear at the plug hole or holes, this saves you pulling the head of the good side, turn the engine one revolution by hand after a day in case of an open valves and water running out the exhaust. Kiwi Tony.