Here's another version that will work on a Superformance. More so for folks that don't have welding equipment or access to same (and skills to use them, people like me!). Took a 15" oval air cleaner bought on eBay with its no-brand 2" washable element. Had the base/riser milled off by a local machine shop. Then I drilled two 1.25" holes to clear the float bowl adjustment screws. I added rubber grommets (for a valve cover breather) to isolate them and eliminate all vibration.
Running an Edelbrock RPM intake with a 1" spacer, and I still have at least 0.5" clearance at the top edges.
-Dean