Have you checked for any cold spots on the radiator with your temp gun? How close is the fan to the radiator? The only reason I found that made any sense when I too was looking at crossflow rads. was the tube length is generally longer so more time to get the water cooler. That would make sense since newer cars have less frontend height so it would make it necessary on certain models. On our era cars though I don't think it would be anything necessary more than just a good working standard downflow rad.
