4.5-14 is about the lowest I'd go. To me a 4.5-14 or 6.5-20 would be ideal on a .223 bolt action. Now that being said, I really like the Burris FFII 4.5-14. You will get better glass and imo just a better scope all around than the Nikon Buckmaster. That's probably the way I'd go, but there are a couple decent 6.5-20 scopes out there as well.
IMO 8-32x is a little too much unless you will only be shooting long range. That's just my opinion though.
Another good option if you want to spend quite a bit more would be the SWFA 5-20x50 scope. It's a great choice with a great power range as well.