NOS Mr. Norm's Tri Power Air Cleaner/Filter $$$$$
I did this with the Baldwin filter. Works great and is a better color then the K & N, in my opinion. Took out about 6" of filter to start, and then about an inch each time after that. Once it was correct size, I made sure to "fit" filter in housing, so the seam was in rear like towards windshield. Once it was to my satisfaction, I took some black Mopar silicone and sealed top and bottom rubber, making sure to overlap the wire screen over paper filter. Not factory, but I like it alot better then the purple K&N. Also, had interference with a K&N rubbing Underhood frame of the hood.
More pics in my previous postings, but you have to go back (2005 or so) a few years? That was when I was searching for a drop in filter.
Also, on EBay, there is a guy that restores all air filter housings for muscle cars. Asked him what filter he used on the 1 he had for sale at the time. Told me he just tried several round filters, with correct height at parts stores till he found one that fit. Then he formed it inside of TriPower housing... he never would tell me what number he used.
Hope that helps someone out there, or at least expanded some choices...