Marlon,
As mentioned you are getting some great advice in this thread. If you are going semi custom/custom route, I forgot to mention the GAP 10 last night to you. You're very likely to get 1/2 MOA capability out of it, and GAP has one of the best reputations for custom guns anywhere. The famed Chris Kyle (Former seal sniper with 165 + confirmed kills) uses their bolt rifles now that hes in the civilian world. There are many guys rocking these Gap 10's in full on long range competition. That tells you what kind of accuracy they are getting out of them. Check 'em out here:
http://www.gaprecision.net/ga-precision-2012-custom-rifles/ga-precision-g.a.-precision-gap-10-.html
Another option to explore would be the PWS line up of rifles. They are a little different breed as they are a gas-piston rifle setup, but they are phenomenal rifles as well. I'm sure you can google up some reviews on them. They are more of a custom rifle than a production rifle as well and are made out of Boise ID. If you want I can get you one of these through myself but its going to take a few months (Not always a bad thing to have a gun back-ordered. They are popular for a reason!).
http://primaryweapons.com/store/pc/viewCategories.asp?idCategory=25
None of the guns listed or mentioned in this thread are going to treat you wrongly!
As far as optics go, Nightforce is always a top choice because like mentioned, they are literally bombproof. If you are wanting to engage targets out there at 600+ then I would definitely look at something in the 6x magnification range. I doubt you'll be able to hold 1/2 MOA at 800 yds with a 4x scope. I'm a big fan of the Vortex optics. The razor is right up there in my opinion with the Nightforce, and you get more features for the price point. A solid FFP, Zero Stopped, illuminated, mil/mil or moa/moa scope at a better cost. If you wanted something that WORKS at a fraction of the cost... check these out:
http://www.hellscanyonarmory.com/in...-1-5x24-30mm-illuminated-ffp-rifle-scope.html
They have gotten nothing but stellar reviews and was deemed the "Surprise of SHOT 2012" by the SnipersHide.com crew for CQB optics. I have a few in stock and if you don't like it, return it and I'll throw it on my personal rifle. Only thing I like better about Vortex is their reticle choices are more applicable. The mil-Dot reticle for the Nightforce will work nicely though I still prefer the Vortex reticles.
Good luck with your decision man and like I said let me know if I can help!
Mike