CFM seems to be whatever the manufacturer decides it is. There are no standards or tests that I'm aware of. I have found that the single most important factor in cooling is HEAT TRANSFER, not water volume or flow or pressure (sorry for shouting). The two best ways to draw heat out of a radiator are by 1) increasing the air flow through the radiator and 2) increasing the area of the cooling surface. The easiest way to accomplish these is by making sure that all available air flows t-h-r-o-u-g-h the radiator, not around or worse yet, over.
I would look first to shrouding the fan and sealing the radiator to the body. I speak from experience - a 608-HP 496-inch FE BB in a B&B that has never seen 205 degrees in southern Cal in stop-and-go in the summer
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Brian
(notice the correct spelling of Brian, not like they spell it in OK
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