Assuming that the radiator is big enough for the engine?
Will vary somewhat based on the shape of the nose, exposed radiator core area, air exit path away from the core, etc.
For core area start with 1 square inch per anticipated HP. Of course, this is impossible in those cars - the largest radiator that fits the stock opening is simply way too small. Making the core thicker is a band-aid, can only do so much. A 1,000 HP car can't cool continuously at any large throttle opening.