How big to make the hole in the hood?

I'm with you on the thought, except my truck isn't mobile yet. I've got plenty to do before she's back on the ground. I'm picking at bits and pieces as time allows. My initial plan is to let the air cleaner stud tell me where the center of the hole will be, drill a 1/4 inch hole there, then draw my circle from that, cut the hole and then position the scoop accordingly front/rear. Hoping to keep it close to the rear edge of the hood.