There’s a guy in Maryland who has quite a bit. Sells occasionally on e-Bay, I bought a NASCAR 56 air cleaner from him 7 years ago. Here is a set made from a kitchen supply store pot lids.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

In lieu of finding an original or reproduction 1956 oval air cleaner, another option would be using the reproduction Hellings air cleaners now being made by Spotlite Kustoms.  Here’s a picture of the original Hellings Stellings air cleaners versus the reproduction Spotlite pieces.
 

 

Lorena, Texas (South of Waco)

As far as I know, and what I've owned  57 "E" has large round air-cleaners.
56 Ford over the counter 2 x 4 set ups has oval air-cleaners.
FYI  "E", Ford car, and T-Bird had different air-cleaners, they look almost the same. The T-bird unit was reproduced some years ago, the Ford car model was not. 

A mate is chasing an oval air cleaner to suit E Code .Anyone have one for sale. ????

yblocksdownunder