Cowl induction

I want to run a cold air induction setup on my 63 Dart. I don't want to put a scoop on it and don't really have the room to run any ducting past the radiator so I was wondering about using the air from the cowl vent by making a couple of holes into the cowl plenum and ducting them to the air cleaner.

I'm not sure that the vent opening between the wipers has enough area to flow sufficient air although it is in a high pressure area which ought to help.

Does anyone know how to work out the required area to supply the engine with enough air? It's only a mild 360 making maybe 300-350Hp