If you want to endure those yamdankee winters with no heater, go for it- - - -there's a reason people in Tennessee live here, and it has something to do with snow only sticking around for a day or three at a time! Just run a loop hose to circulate the coolant back to the water pump inlet from the heater outlet fitting. If the heater fittings are simply blocked off, it will create dead spots with no circulation and make the tendency to overheat more severe.
Jerry