Jimmy,
I was at the FW PNP today. Was your donor car the maroon one? That was the only 123 today. Looks like good MBtex on the back seat but the same issue with the foam feels crumbly. Those covers don't look too hard to R&R. Couldn't you refoam (use closed cell) in two steps with the first making the ridge pieces and #2 glue them to a solid second layer? Just a thought.
BTW went back to the other PNP and found all my blue interior items (assuming a 116 has the same seats - I measured). Gave up on the 190 idea.
Charles