If tere is even a slight bit of wear between the rocker tip and/or the valve stem tip, you will get some slight ticking. Tightening the valves won't make it go away just make the run condition worse. As far as the vacuum surge, one quick check is to take your hand while the engine is running and slight lower it over the primary side of the carb and creat a choke style condition. Raise and lower your hand to restrict the air flow ever so slightly and watch the vacuum gauge. A lean idle circuit can cause this stumble and fluctuating vacuum reading.