Now I use a Wix Racing 16"x3.5" filter in a homemade box, taking air from the grill area (no more hood scoop for me). AFR no longer richens up at the top end of the 1/4 mile, no speed or ET lost (ran 132.5mph at the recent bracket finals at woodburn.) It's a little different Carburetor is IN the airbox, bottom of the box is sandwiched between the carb and intake. Underside of the hood IS the top of the air cleaner (about 2-1/2" clearance for carb top). This way the filter element is as high as possible. Airbox just lifts off once the hoses are disconnected.
One nice thing about running an air cleaner is that it shows you the items that WOULD have gone through the engine, all trapped outside the filter. To generate some pressure I fabbed two panels that closed off the areas above and below the grill, making it a closed space. Air coming into the grill has to go through the air cleaner or radiator.