New and Improved
So here is how it goes the K & N filters that I mention earlier both fit the AC Housing. If you want a cheapo paper filter the only one available is from Sunbeam Specialties it is a 1.5 element. As Bruce said there is no part number on S.S. item period. I have not seen it in person and do not know what color the gasket is so it's go to the biggest and best stocked auto parts store and spend time searching for one that fits. Call it job security putting no part number on a part.
I just installed a 2" K & N 3710 filter on my car and it fits with room to spare. Most guys due to a combination of manifold, carb., engine mount heights can't fit more that 1.5 filter and housing under the hood. No, K & N does not cross check to other filter types.
Here is the data on how they rate: Their numbers
E-2859: approx. (1.5in), 381CFM @ 1.5” of water ( stock replacement )
E-3710: approx. (2.0in), 508CFM @ 1.5” of water
My car has a 600 CFM on a 302 with moderate build so I am a little choked by even a 2" filter.
Given these numbers I would guess paper filters are somewhat lacking in flow for hi HP WOT use
New and Improved
I have a stock AC Housing reproduction that I was going to cut the bottom out of to increase flow keep stock look and be the new and improved model. A custom foam or paper element will line the bottom area of the are shaded in blue tape. The area increase is about equal to a 3/4 " gain The Duke has a 347 that everyone and has offered to swap filters around during his next Dyno test. But If Duke does not live up to a past threat to "use K & N filters for traction,"

We may get some real numbers on the what's hype and what's not.
I have put the whole project on hold mostly though as CAT parts will soon be selling the housings and the modification is low on my to do list, unless I get an assurance from Duke he won't drive over my nearly 50 dollar air cleaner
Most guys have a track filter and a car show filter, and prop open the hood when in race mode as well.
Pics added later,
Sorry, I know you just asked for a part number but I understand you are going 347 big but maybe want some original bits for show.