I am thinking that a purpose built long range 06 with heavy bullets can beat a 280AI
I would enjoy exploring that debate.
I think the B/C of the 240smk is over 7.
A great deal of what influences my thinking these days is component availability and cost. O6 cases and 30 cal bullets; can't get much more generic than that.
For that use, I would choose a 300 Wea length action and mag box.