Correct Simon, but also notice that even back then, designers knew that the air used from the cowl for induction had to be separated from the engine compartment.
It seems to me, the diagram Sin posted with the 'Vette, the airflow is used to help with reducing lift by putting more are over the top of the car rather than it going out under the car. But now we are getting on a slippery slope of functional, race car aerodynamics- not the original topic of OE designed air flow to keep a street car's cooling system working efficently and how a dumb ricer mod negates what engineers have designed into the car.