That'll do the trick.
Look at the way the sides of the grille are shaped. Assuming that the radiator and radiator surround act as a dam so that air must flow elsewhere than through the radiator, it's quite clear that a large portion of it will spill out to the sides, leaving the forward pointed top center in relatively clean air. Yes there is a boundary layer above the hood but it isn't anywhere near 14" thick on most cars. A Mack truck, maybe. The reason the cowl induction works is because the air that flows over the hood piles up on the windshield. If the boundary layer was even 6-8" thick it just wouldn't work. In about 1972 Hot Rod magazine did an article on hood scoops and spoilers where they did testing to see how effective they actually were. I don't recall their methods, but because at the time I drove a 1970 Olds Cutlass with the scoops and spoiler I remembered that their results showed that this was one of the very few cars on which these pieces were functional. The Olds (442) hood had openings about 1-1/2" to 2" tall and quite wide, spaced maybe 1-1/2 ft back from the lip of the hood and the area in front of the opening had a smooth downward curve to a sharp cut-off. Probably the scoops only caught air in the upper part of the scoop but they were wide enough to make it work. So it's more a matter of finding the edge of the boundary layer, and that is going to move around a bit. It could be as close as 1/4" from the hood or as far away as several inches. In this case, with the sloped back sides of the surround and the forward jutting top center, it seems to me that there won't be very much separation at all before the airstream gets caught in the scoop. It should work very well.