I am planning on building a gun up from a Remington SPS Varmint .308. I am going to put a B&C Light Tactical stock on it and a Rifle basix trigger in it. My question is what kind of glass do I need for this gun? I want to be able to eventually shoot it at about 600 yds, but will probably be staying with the 300 yd range to first start off. I need a good budget scope. I am trying to do all of this for under 1500, I realize I might have to stretch that a little bit. Are there any other things that I need to be aware of to do that makes a good gun?