Well, that's a heck of a scope for an AR. I'm guessing you are going to be doing some long range gunnery.
Larue mounts are pricey, but IMO, well worth the money, plus you get some free stuff!!
As for the mounting, you can skip moving the front sight, the scope is just going to be mounted higher. If you're ok with that, go for it. I run a Burris red dot on a flat top Carbine on 1" rings, and the dot falls about .5" above the front sight post. It limits the field of view below that, but never been an issue for me. A couple days ago, a friend and I shot targets at 310 yards with only the red dot, or iron sights, we only missed once out of 30 rounds each. (The one miss was me trying to shoot a comtrolled pair, bad idea)
As for the optic, you can't go wrong. I have a Viper 6.5-20 on my Remington 700, and have great things to say about it. I give it an a+.
As for the elevation riser, i'm sure you can. No personal experience with it. You can get Burris risers, at .5" that are Picatinny based, and great quality.
Enjoy.
