Well that by far is one of the pimpest rifles there is this year. Is it worth $1850?????? You dont care if its long or short action, so I wouldn't get any of those calibers you mentioned. You are obviously building the gun of a lifetime or you just have to much money
If you are going to use it on elk and bear I would jump up to a minimum of a 270wsm or 300wsm for a short action and a 300 win mag for a long action. I personally would pick the 300 wsm for the short bolt and the power and distance of a 300 mag. The ballistics are awesome and you can get big heavy grain bullets. The ones you mention just dont have the umph as the magnums.
Scope, good luck on that finding a silver one. Why not black with silver rings and bases? I would get a Swarvoski, kahles, or a tactical leupold you could dial in. You are getting my dream gun from the off the shelf rifles! Let us see it when its put together.