You could rebarrel to any of the other SAUM rounds but to make it anything else requires bolt face modification or replacement adding extra cost. Your best best is to trade it for what you want.
To expand on what greybeard said. Changing out the barrel will also require changing out the bolt and the magizine follower if you were to go to a 308 based shell (243, 260, 7-08, 308, 338 Fed, 358 Win.) or other short cases like 284 Win or the whole host of wildcats based on it.
My question is rather than trade it off and get what you want loosing $ in the process.
Why not just reload for the round and reload to 30-06 load levels. only would cost you a reloader and dies.
There will be a payback for the reloader especally with the 300 SAUM rounds and you already have cases.
there are a wide variety of .308 bullets out there for deer from 125 grain to 180.
There should be some loading data to get the 150 to 180 grain bullets in the 2650 to 2900 feet per second.
And the reloader can add to the payback faster if you have other calibers you want to reload as well. (pistol?)