RE: German k98 8mm Mauser
The S&K mounts that replace the rear sight leaf will work fine if you lockttight the screws in place.
The sights are real easy to work- put the target on top of the front post centered in the rear notch. Doesn't get much simpler than that. The sights are plenty good enough for deer hunting if you learn how to use them.
And please don't alter the rifle. It would be about as tasteful as your grandfather giving you his pocketwatch on his deathbed and having you take it apart, throw away the movement and repalce the innards with those from a digital watch.