I think the air cleaner that was originally posted is one I have listed on ebay. It is also listed here for less.
Here is a link to the listing on ebay:
https://www.ebay.com/itm/352222787499
....and the post here:
https://www.yenko.net/forum/showthread.php?t=145359
This unit is a 1967 Camaro unit with the 4 windows.
Here is another that just sold:
https://www.ebay.com/itm/362153385563
These cowl plenum air cleaners were race parts. Someone certainly could have bought one from the Chevy dealer and installed on a Nova when new.
Thanks,
Jason