The new cowlboard has an embossed pattern but not that, or the wrinkled "leather" pattern that was in my Aero in a couple locations.
Do you have a picture by chance?
Here's close-ups cropped from a couple recent shots. First one is some old trim pieces from the bottom of original '52/3 arm rests, which I describe as having a " wrinkled leather" pattern, on top of the modern cowlboard I was cutting new ones from.
Second shot is the new board under my dash.
Both locations had the same material, black all the way through and ever so slightly thicker than the new stuff. I looked all over the place and never found it.
The modern stuff is black on the embossed surface only, cardboard colored on the back and cuts at the edges. I blackened my edges with a black marker.
I got mine through a local shop that gets a truck delivery once a month from Activefoam in Chicago (locations multiple states). Miami, and I think everyone else carries the same product.