Running Hot

The part that gets me is I have a 68 newport custom with a stock 383 2 bbl. This car has 93.000 original miles. Ican drive it on the highway at 80 mph all day and it won't over heat. It can be driven in bumper to bumper traffic in the heat and it won't overheat. It never has left a coolant puddle under it. It also has a smaller rad the the valiant and it has no shroud. Something to think about.