I won't take credit for it, but Chris B took a Mustang radiator and laid it down so the top tank sits just inside the front cross member and the bottom tank is just above and in front of the front axle. about a 30 degree angle. It has an electric fan mounted to the back and a simple grill on the front and uses a remote fill on the engine. I repeated the same thing on my '59 150 with a 225 V6 odd-fire and it works pretty good. Two things I would do differently now, either an aluminum radiator or heavy duty core and a air scoop to direct a little more flow up in to the radiator. I think at speed (40-45) the air goes under it instead of through, below 35 the engine runs at 180 degrees. above that and in overdrive runs at 200-210.
Something to look at that is less than a custom radiator and doesn't require any sheet metal modification.