340 tooooo hot

Is it a new water pump or an old one? Pull the spark plugs and what color are they, white means engine to lean so richen it up 2 sizes. The engine running down the road should not overheat unless the rad is to restrictive and not allowing air flow through also check to make sure that the hose coming off the bottom of the rad to the pump has the steal coil inside it to prevent the hose from collapsing. One other thing, since you're going to have to drain the system to check the hose, pull the thermostat and check that it is opening at 160 in a pot of water on the stove with a good thermometer.

Terry