If it is a kriegmodell, i highly advise NOT to mount a bayonet lug. Yes you can do this, and even without any damage, but if this rifle was made as a kriegsmodell, it should remain as so.
And no, it doesnt mean that it is russian or french captured, that it can be altered. The only thing these countries did, was the removal of the sight hood & cleaning rod.
We need more information tough, but looking at the exterior condition, thats a good price.
We need to know manufacturer code (On reciever) and year, & barrel condition