You can't really "over" stabilize a bullet. That being said, I'd find at least a 1 in 8 twist. It will stabilize as much bullet as you'll ever need for a yote at 300yds. I'd strongly recommend getting an armorers guide and just building your own from parts (at lease the lower, monkeys can put a lower togather) it'll save you a bunch of money that can be put toward good glass. I'd also stick with a 16in barrel if your shots will be under 300, they handle much better than the longer tubes, and are lighter. If your only going to have one AR, I'd stick with 223/556. As for glass (as said above) something with a 2x or 3x low end is pretty nice. The Nikon M223 or Leupy Mark AR are good ones for the money and both have turrets that are matched for a 55gr bullet (Just figure up a drop chart if you deside to run heavier bullets) Just don't be stingy with your glass or your trigger. My favorite yote rig is a RRA upper in 223wylde, 16in HBAR barrel, Spikes lower with a JP Enterprises Competition trigger, houge grip, Magpul CTS stock, and a Leupy3x9 Mark AR. I wouldn't nessisarily trust my life to it, but it's easily a sub MOA rig, and has taken a ton of yotes and gophers and never had an function issue. It might not honk your hooter, but it's been outstanding for me.