I guess one way you could do that is to design a crossover pipe that feeds both heads. That crossover pipe would have a single inlet hose going to the top of the radiator. You would still have the problem of how to to distribute the water leaving the bottom of the radiator in large enough amounts to get pumped thru the engine in order to keep it cool. Perhaps a high volume electric water pump is part of the solution along with a reverse flow cooling system.
I would think it would cost more to make all the necessary modifications to a single inlet/outlet radiator. Why not just have the original style radiator redone or get a new OEM style radiator?
Roger, I'm not using it in a car. Just needed a radiator for my test stand and since I had the Mustang radiator, it was an experiment to see if it would cool the engine. It works fine. Ed