Here's the solution I came up with:
Had the airhorn on the base machined off. Then I carefully measured where the float adjustment nuts hit it and used a one inch hole saw. Then used 1" valve cover/PCV grommets to fill the hole and it's a nice snug fit. Drops the air cleaner a good inch and even with a one inch carb spacer I still have a good 1/2" of clearance at the worst point (front edges of the lid).
Also, this solution still provides enough clearance on the throttle arm side...no relief machining was needed.
-Dean