i was reading on novak adapters and they said that a radiator should be have a minimum square inch area as the cubic inch of the motor plus 50 more square inches for adequet cooling so with a 455 you in theory need 505 square inches to cool it "good enough" hope this helps. and btw the number of layers does noe matter just the surface area shown to the cool air and that is all. as the more layers the radiator has just means that the back (closest to the motor) has hotter air passing over it then the front most layer. any way for more info go to novak's site.
-brad
'86 & '98 Ram 4x4's