Chambering aside (and you've gotten good advice on that - certainly change that up):
It kinda depends. What's the shortest range that you want to be able to shoot at? If the shortest range is 300 yards or more, then a fixed target scope in the 30-50 power range. On that budget, Sightron SIII or SII Big Sky, Leupold, Weaver, etc. if you want to be able to shoot also at "normal" ranges (under 300), then a variable.
Without know more, I'd say probably this one:
http://swfa.com/Sightron-36x42-SII-Big-Sky-Riflescope-P11091.aspx
Back on chambering, in my understanding, quite a few people do reasonably well at 600 with 1 in 7 twists and heavies (80-100 grainers) in .223. But it goes to hell in a handbasket not too far past 600. The BCs just aren't there.
and I want to be able to shoot at 1000 yards.
It kinda depends. What's the shortest range that you want to be able to shoot at? If the shortest range is 300 yards or more, then a fixed target scope in the 30-50 power range. On that budget, Sightron SIII or SII Big Sky, Leupold, Weaver, etc. if you want to be able to shoot also at "normal" ranges (under 300), then a variable.
Without know more, I'd say probably this one:
http://swfa.com/Sightron-36x42-SII-Big-Sky-Riflescope-P11091.aspx
Back on chambering, in my understanding, quite a few people do reasonably well at 600 with 1 in 7 twists and heavies (80-100 grainers) in .223. But it goes to hell in a handbasket not too far past 600. The BCs just aren't there.