Thanks for the prompt reply, Ed. In a conversation with a radiator manufacturer, I was told that the core elements of a radiator for an LS3 would need to be 3 inches thick. This stock, original radiator has core elements that are 2 inches thick. One thought was that I might trim that top, horizontal brace of the radiator frame from its current 1.25 inch thickness to half that (5/8 inches). That would allow me to move the radiator an additional 5/8 inch more forward in the frame, minimizing the intrusion of the thicker radiator into the space between the back of the radiator frame and the front of the engine block. So I THINK I can accommodate a thicker radiator, but I am still in the dark on upper limits for a taller radiator.
