J'ville, about the difference in diameter of the modern aftermarket air cleaners; Why not just fabricate a plate with an outer diameter to fit the modern air cleaner housing and the inner diameter to fit the top of the carb? That way you can keep the original oil bath cleaner and "go back" to that with very little effort. What Mickey3d and I are thinking of are the Oldsmobile air cleaner housings that had to air inlets, one on either side and they were sometimes described as "batwing" air cleaners. I will try to find a picture and include it in this post if possible, or at least a link to one. If this is different than your air cleaner then nevermind.........anyway.
http://www.grumpyzgarage.com/movin/parts-002.jpg
There was also the dual quad air cleaner that was called "batwing" but it looked different.