Ditto on the ranges. I have 16 inch AR that I shoot out to 800 yards without problem using a 1-4x optic. With a bolt action with that long of a barrel you will definitely have a capable rifle. As far as the optic is concerned that's really up to you and in my opinion needs more definition. If it's an option I would go look through some various optics in person. If there is the option to do so look at things at range and see what you think. A local to me store has a big wide open space and they will let you walk to the front and look through scopes at various distances.
Also it's going to depend on the type of shooting you want to do. If you are going out to be social and live the life of a retiree picking up chicks then you have a lot more options. If you are like some folks they still get somewhat 'competitive' even with things like shooting groups or whatnot then that could impact your decision on optics. Same as with dialing up vs hold overs (or a combination).
Again, it in my opinion needs more definition of what kind of shooter you are/want to be.
Another thing that you didn't mention is if you reload or not. Ammo is a big deal and ".223" is a wide net that covers a ton of ground. I mention that because if your goal is to just bang on the steel with factory ammo that's one thing, but if you are trying to get groups that's another. Basically my point is it's not whether or not a specific component will work or not, but rather will they work TOGETHER for you?
It's been my experience that if I start with a goal in mind, then I see if the ammo I want to use (including reloads) works for that goal, and then after that start looking at optics and rifles.