Your 270 Wby can do anything a 280 can do except have a larger diameter bullet....
Really, it would be more cost effective to either keep it as is or buy/build a 280. The added cost of changing the bolt face to .470 is so much that it offsets any other costs.
Plus, who doesn't want another gun!?
The cost break down should go something like this:
Change bolt or buy a new bolt: $300
Remove old barrel, thread and chamber: $250
So MINIMUM of about $550 without the cost of the new barrel which will be $450 ish so total will be $1,000 range.
Buy a new 280 $800 to as much as you want to spend.
However, if you are truly done with 270 Wby chambering, have it changed to a 280.
I think the most cost effective would be to sell the 270 Wby and buy a 280.