COLD-CASE Radiators - Looking for advice and user experience

I have a 440 in my 70 duster that I race, i currently have a griffin aluminum radiator, mercury mystique type electric fans with separate thermostatic controls, a flow cooler water pump. I run E85 and aluminum heads and yet I still have issues with the motor getting too warm. I can only guess that its the radiator at this point. This motor is aprox 650 hp. Can you steer me in the right direction?