Aerodynamics sort of
ANY Benefit? Yes. Especially if you "block off" all the way out to the trim instead of just covering the headlight hole. (Think the dodge charger 500 and how it lost a bunch of drag by pulling its grill out towards the trim/bumper rather than leaving it recessed.) But considering the rest of your A-body is still shaped like a brick I would say it's negligible here. Just go with whatever look you prefer