I've worked on a few of LSR Sniper Clones, and I have handled several other LSR Sniper Clones that I haven't built. I am also working on restoring a bcd4 LSR Sniper (original barrel/receiver and scope).
If building one, I'd try to find an RC bcd4 or CE rifle. bcd's are much more common and shouldn't be too hard to find.
The mount your looking at on ebay are the ring style mount (early mount) - they then added the rings to the original scopes as the scopes would slide with recoil - eventually they went to a banded mount (as pictured in the reply above - there are both wide and narrow band variants).
If looking for an original scope - DOW scopes are the most costly, bek scopes are are somewhat common and can be found at more reasonable prices. There was also the AJACK as mentioned and some Zeilsechs scopes.
What I hate about these reproduction mounts are some are excellent and some are sh_t!!!
I purchased a set from the Ukraine (about 6+ years ago) and the scope was repro but was marked Zeiss Jena and the upper and lower mount even had the correct waffen amt applied.
I hope the seller is being honest and the mount is actually from the Ukraine - then you should be getting a decent product.
The reproduction scope as previously mentioned is not correct but looks the part. Shotgun News had an article about 7 years ago as a company was making reproduction LSR's with these repro mounts and scopes - some were imported into Canada and sold for 2K. The problem is no one I have seen makes a good LSR Banded mount period!!! I've bought three and all were horrible and originals cost $2-3K just for the mounts. But as I stated - some Ukraine fixed ring mounts are very good. The Chinese mounts - not so much.
Many of these repro scopes will not stand up to the recoil of the 8mm mauser. If you want it to look good - purchase an original scope. If you want to shoot it - get a WWII period scope or early post war scope.
Another option is Corwin arms has a great SSR scope mount (about $150). This mount was made in Eastern Europe. I had a friend who had an original CE SSR with missing top mount - he purchased the Corwin mount and used the upper - it slide right on - with no fitting and once aged looks the part and was an excellent find for finishing his rebuild.
For $150 - you would have alot of cash left over for a real period scope (better quality). Correct rifle for an SSR would be a CE42 - scope would be an AJACK or Zeiss Zeilvier would work
If you do stick with the LSR project get your cross hatched butt plate and safety here:
https://waffenmeisters.com/index.php?route=product/category&path=59_60&sort=rating&order=DESC
They make an excellent (not exact) product which generally does not requiring fitting and they provide good service.
Good Luck