It takes A lot of wear to render the 98 Mauser wing safety non functional, but it can happen. If this has happened, you will have to replace the safety, or the cocking piece, or both (or add metal by welding and then reshape to function).
I have scoped a lot of mauser sporters, and unless you have something really odd, the regular wing safety will still work with a scope installed.
However, it won't work all the way like it did before. You lose the ability to lock the action shut with the safety on.
The safety wing will hit the scope when its about a 45 degree angle, so you also lose the "detent" feature holding the wing in place when its straight up and down, as well. But, at the 45 degree angle, the safety is still camming the cocking piece back slightly, and does keep the rifle on safe (won't fire when trigger is pulled).
The biggest problem with the standard safety lever and a scope is that the end of the wing is rounded and smooth (98), and does not give a good positive "grip" for your fingers when its pushed up against the scope. So this makes taking the safety OFF a bit more difficult.
I have used "scope safeties" from Numrich, and Beuhler (mostly Numrich) they are simple to install, quite positive, and they have a "shelf" which is easy to work in the ON position. And they are fairly cheap.
The down side is that they are fairly cheap, and while absolutely functional, they don't give the high end custom look. A Model 70 swing type safety is very classy, but they require replacing more parts, possibly gunsmith fitting, and are much, much more expensive.
Installing a trigger with its own safety is another route, also more expensive than the scope safety, and requires inletting the stock (removing wood to give clearance to the safety).
Just remember that after you have done all the things to make the rifle you have into the rifle you want, some milsurp fanatic (or maybe fanboy would be a better word) will come along and berate you for ruining a valuable piece of history!
IF this does happen (and it seems to happen a lot) just smile at them, as they rant, and when they wind down, stick them with this, "you ought to thank me! I just made your milsurp more valuable!"
Or be creative, and polite until they get bored and leave.