You'll probably need some way to elevate your cheek - either an adjustable comb, stock pack, something. It can be done if you want the 56. Every Nightforce has a 30mm tube.
Edit - I am interested in putting it on a Savage 110BA, which has an adjustable cheek weld.
In that case, no, it's not too high. Take some measurements and make sure you get high enough rings so the bell clears the top rail/chassis thing, then go for it.
Here's a guy with that setup: http://www.snipershide.com/forum/ubb...54301&page=all