Yeah, a nifty air cleaner setup is extra-nifty on the twin-carb intake, but y'gotta have a setup that actually cleans the air. That writes velocity stacks right out the question, along with any of the K&N pretend-filters or lookalikes.
Can't find it at the moment, but somewhere on here or .org there are pics of the setup someone put together from two stock '63-'67 "small 'n' tall" air cleaners, winding up with a big oval assembly that looks like some of the 6-pack air cleaners. Looks slick as all hell with the paint and decals, and it actually filters the air.
Even slicker might be those twin oval offset air cleaners used on Chrysler's twin-carb setups of the late '50s.