heater hoses, 1973 dart swinger small block

yeah you might be right the factory one doesn't have a control valve in it that has a heater bypass. so even it I do sop the flow one way the other is still open right? because the issue of having a defroster, and heater in cooler moths, and rainy days, would be nice, could I stop vavle both sides of it, and open I cooler months? like a ball valve?