Body & Paint guys---Inside cowl vents?

The car is a '63 Falcon which has a hollow cowl/air vent channel inside the top of the dash. The vent grille is integral to the sheet metal. I'm sure there are a lot of cars with similar construction.

How do you clean-up, prime, and paint inside this thing? I don't just want to shoot paint through the grille from above and hope for the best.

 

welllllll..... you can take the fenders off, take the heater box and driver's side airbox out, and reach about 10% of the internal area of that design. if you make a spray head that has a 90degree outlet on it and put it up in the vent openings, you might be able to get about 25% of it with any certainty.
or, you can remove the windshield, wipers, hood and fenders; cut out about a hundred spotwelds, take the cowl top off and de-rust it and the inner cowl, prime it with weld through primer, paint the areas that won't be welded and then reinstall the cowl top.
Ford didn't do anybody any favors designing the cowl air intake here.

 

Saw a Comet guy who took off his fenders and carefully cut access holes to the hats on the cowl ends. Once he finished, he tacked the removed covers back on in several places and used body seam sealer over the entire piece in the event he had to remove it again later.
Another idea was innovated by Dyno Don who cut sections of the cowl 'boxing' out just below the grill area. Once the hood is closed you can't see it. For further detail, refer to Popular Hot Rodding magazine, October, 1965. There's a good shot of it and it acts like a poor man's cowl induction as well.