Not that it responds to the original question, but I think that the original twin nostrils resulted from the spare tire required by FIA when the original GT was designed. The tire was layed flat under the front bodywork and the two outlets exhausted the radiator air from around it. Early plastic models of the original car in the '60's demonstrated this. (shows how old I am)
The nostril shapes changed and were ducted as the car was developed and were finally changed to the single nostril for better cooling when either the tire was moved to a more vertical orientation or removed entirely from the front when allowed by a rule change (I don't know which).
Thought this might be interesting.