Well, it's interesting. The caseback pictured in my prior post is what's fitted to my 116520 rep case as it was rec'd. It's very much the same as my MBW 16520 EP400's caseback. Unfortunately, since I picked this case set up used, I have no idea where it was originally sourced from. A shame as I'd like to buy a couple of spares for my own inventory as well.
As for the bezel... I replaced my old MBW 16520 bezel with a genuine bezel, so I was planning to either use that, or if I'm feeling splurgy I'll pick up another gen to use:
MBW bezel:
Genuine bezel:
Physically, the bezels are the same size, shape, etc.