Here's a thought for the top. Make it so the opening sticks straight forward. Put a 2"-3" adapter and a few inches of 3" pipe. Then maybe even a 3"-4" adapter and a few inches of 4" pipe. Make it into a "speed reactive supercharger".ÂÂ
I was reading an article on Hi-po street bikes and the ram air intakes they came with from the factory. The magazine (I can't remember which one it was) did an unscientific test on a dyno. First, they ran several bikes on a dyno to get a baseline number. Then they ran all of the bikes on the dyno again with a pipes connected to the ram air inlets and air blown down the pipes at 150 m.p.h. The larger displacement bikes didn't experience as much of a power gain as the smaller displacement bikes because they were able to use more air than the fans were able to generate, but some of the smaller bikes gained as much as 10 h.p. Not that you will gain 10 h.p., although you may because you are using a much larger opening, but I bet you pick up a few h.p. Maybe even enough to offset what you are losing by having a snorkel in the first place.
Just think of it as a fart cannon on the intake side of the engine.