I would do a 280 AI. Now that you can buy preformed brass(nosler) and don't have to fire form that is a difference maker.
Very efficient round, almost a 7RM and burning less powder.
With the '06 being obsolete and the .270 accused of less than manly status, the .280AI is the obvious choice...
Serioiusly, if I didn't already have a very good 7RM and if I was going to build on that action, it would be the .280AI.
DF