I would disclose what was done (and why), as well as offer the original parts if wanted. That is how I'd want to be treated as well.
The only other BBS I spent a lot of time on was for old Buicks, and numbers-matching was a big issue for some people, regardless of condition. I don't know if most camera buyers/collectors are that enthusiastic.
Even if it works as advertised, I'd want to know if the camera/lens was opened up (even for factory service). A coworker bought a FED on ebay. The lens was a bit out of focus, so he disassembled it and found signs the seller had tried to adjust it himself. He really would have wanted to know before the sale.
Finally, I had my 35mm with stuck shutter and light leak "serviced" by a pro-shop that advertises camera repair. After three tries they did not fix it (I figured it out myself). They did replace the back, but I suspect they did not replace the shutter as claimed - which is good for me. You see, I inherited the camera from my Maternal Grandfather, and it has a lot of sentimental value; there is the whole Theseus' ship issue for me.