There will be no Soviet markings on a captured K98k. The only mark the Russians put on the captured rifles was a "x" on the left side of the receiver, representing two crossed rifles. Most of these rifles will have the swastikas pinged out, and many will have parts refinished in red.
Another thing you have to decide, is if you want an early or late production rifle. Early rifles have parts made of solid steel, instead of the stamped parts of the later ones.
Sometimes, some of the typical Russian capture features I mentioned above are missing, for example it appears the Russians didn't put "x" marks on all the captured rifles. In these cases the rifles can be identified by the other marks, such as the red refinish.
Hope this helps: Tom