Be careful about ANYTHING entering the driver's compartment from the cowl area.... For years on our Vega, we had an opening in the cowl for the purpose of pressurizing the cockpit with air (we all know that the cowl is a high pressure point on the front of coupes and sedans) ...it did what it was supposed to do quite well....
Now.... enter some new inspectors who have the thought that a fire could come up the back of the firewall and be pressured in to the cockpit theough the open cowl.... (plauible, I guess) ....They, from that point on, required the cowl area to be sealed from/to the outside..... We now take the air through a metal tube from the front of the car....
There are other ways it can be done as well.... we considered a small hole in the roof just rearward of where the roof curves up from the windhield and about two inches toward the axial center of the car drom the driver's door that would have a tiny forward opening/facing scoop shape..... several cars have setups like this but we figured that, if a regular fire could go int othe cockpit through the cowl, a BIG fire could come up and over the roof and enter the car through there as well.... so....
Lots of ideas....