Well, I would suggest to get the best optics you can afford but that probably goes without saying.
Do you plan on shooting you .223 out to 600 yards? Is that a reasonable expectation from the rifle? I mean, I don't know the twist rate but if it's anything less than 1:9, 600 yards may prove to be a bit frustrating. I don't usually suggest something that may have to be replaced in the future but in all honesty, if you've done most of your shooting at 50 yards or so, I'd probably suggest a higher quality lower powered scope than a moderate quality higher power scope.
I also used to think that longer distances required higher powered scopes until my buddy (benchrest competitor, best rifle shooter I know by a long shot) told me he did almost all of his shooting either with a 6x scope or a variable set to 6x. He can get itty bitty groups at very long distances. I've seen him shoot 1" - 1.5" groups at 300 yards with his .25-06 and the scope set to 6x. Not trying to talk you out of a higher powered scope or anything, but I just kinda got the feeling that you had written off anything other than a 6-24x50 scope and that really isn't needed.
If the gun is going to be used purely shooting at paper, then a variable probably isn't needed. I'd personally probably go a quality fixed 6x scope. The same buddy has one of the Leupold 6x scopes on his medium weight 25-06 (25-06 is his cartridge and has three of 'em) and with his handloads, I really wouldn't think anything within 600 yards would have much of a chance from him. They even have one with target turrets priced at about $400. I used to have a Burris Signature fixed 6x scope that came on a rifle. This was back when I thought everything should be variable. Only scope I regret selling. I think they go for about $300 nowdays.
I'm a big fan of the Weaver Grand Slam series of scopes. I have three of their 3-10x40 scopes on various rifles. At $240 a pop, I think they are the very best value of any scope, period! But no target turrets. They do offer a Tactical series (with MilDots, adjustable objectives and target turrets) but the prices go up pretty quickly. I think they start just under $500.
Probably the best price on a decent quality scope with target turrets I can think of is the Bushnell Elite 3200 10x40. Matter of fact, I had it on my 10FP in 223! Very clear but not up to the Weaver Grand Slam level of optics. I think I paid $200 including flip ups. It is on the shorter side and someone commented to me that it looked too small to be a 10x and looked kinda dinky on a heavy barrel rifle. I don't really care much about looks of scopes but it is pretty small. It's the second one back in the picture. As a point of reference, the scope in front of it is a typical 6-18x scope and the two behind it are both 6x42s. Both of the 6x42 scopes are larger than the 10x Bushnell! I could recommend the scope, but I would recommend the 3-10 Grand Slam if you were willing to not have target turrets. You can still count the clicks.