The scope power range being an 8x won't much effect on the elevation. You just need to look at the specs of the scope and looking at it there is 90 MOA or 26.2 mils, whichever you are using. Both of those on a 20 MOA base will be more than enough to get to 1000. Even on a flat base it should do it but if running a .50 you might as well go at least 20 MOA if you wanted to reach out past 1000.

The Razor II 4.5-27x would work as well. It has 28.5 mils or 71.5 MOA. Again both more than enough on a 20 MOA base to get to 1000. Both should be about in the same price range but you could probably get the Razor II cheaper as they are about $1650-1800 street price now.

Actually I just looked and the rail on the 99 is 27 MOA so you can go with a set of rings or mount with 0 MOA. Actually probably a good idea to stay with a 0 MOA now seeing that. Depending on where the scope sits on the rail you can go with differing heights as it is a flat top but also if the scope is farther forward you can use lower as the bell of the objective will be past the rail. Looking at the pic below it appears to be needing a ring/mount in the 1.5" height range but it also looks like he has very limited eye relief so you never know. The 1.45-1.5" height would be the safe bet for a 56mm objective.