AFAIK, the 111/111S decomp is proprietary for that saw family. It's kind of a strange beast at that, too. I agree that what's on there is a 90/910e type decomp.
Here is a pic of a 90 decomp and the 910 looks to be almost identical if not. I agree with Robin on the top covers....very possible to have been NOS as they don't have much missing from them being moved around like the saw probably was. That silver is about the hardest paint in the world to forge. I don't think I've ever seen a repaint where it wasn't glaringly obvious. I've seen close, but no cigar.
And yes, the muffler has obviously been repainted....likelihood of it looking that fresh with a big dent in it is about zero.
But also as Robin said, we've seen some real trashy 111/111S saws go through eBay for that much with things missing or broken. eBay has it's own proprietary realm of 'values', cheaters & posers. It's a world I don't live in thankfully. Scott made me a swinging deal on a 111S, or I never would have had one. Robin got one very similar to this auction except with authenticity and provenance.
So yeah.....did this seller do the research and try to make the saw as original as possible, or did he hook up with some of the forums' known cheaters & posers to deceive? Conversely, Scott always went the extra distance to make everything as OE as possible. How he made that 110 look he sold on eBay was dead OE.
Kevin