I'll tell you what I did. If you look behind the grill of an AD truck, it has the perfect funnel to direct airflow. I bought a brand new truck radiator, conventional, modern, crossflow 3-core copper/brass, and mounted it directly behind the grill of my truck. I used Coolflex hoses as the upper and lower radiator hoses. Then in the original radiator support, I built a fan shroud out of sheetmetal. I also used the same galvanized sheetmetal to seal up all openings around the radiator, to make the fan shroud more effective. Although I used a spacer and fan clutch with a mechanical 6-bladed Hayden fan, I don't see why you couldn't adapt a good electric fan instead.
It works very well and because the radiator is painted black, you really can't tell it's right behind the grill of the truck. Believe it or not, this was probably half the price of having a modern top-flow radiator made to go into the stock radiator support. I spent a little over $200 bucks, rather than over $500 bucks. So not a bad deal, and I've got a lot more room in front of the engine. Plenty of room for oil coolers, A/C condensers, etc., if I needed them.
