I might have already built your rifle....
My 280 - Updated!
If I had to do over again, knowing what I know now, I would have chambered the rifle for 280AI rather than 280Rem.
Two reasons for that.
1. You can shoot 280Rem ammo in an AI chamber.
2. You can almost get 7mag ballistics out of the AI.
Given all the 7mm bullet choices, either of the 280's is a great deer round and will shoot long range varmints and targets nicely.