Trying to figure out why you'd do this - to reduce windage? Would be neat if there's a way to direct the oil from the drain back holes and shield it from being affected by the crank vortex, but in general I'd think you would not want to restrict oil in the lifter galley. Whatever you can do to get it back downstairs to the bottom of the pan the quickest way possible would be what you want. What's the theory on restricting it?