6.5-06, and any AI chambering would be a great idea and you would definitely have something new and different. But, if you're not reloading now or plan on reloading then you'll have a very hard time getting ammo. Out of all the cartridges you listed I would go with the 25-06, very under-rated deer slayer. Just make sure you put at least a 24in bbl on it to get optimal velocity.
If I was to re-barrel a long action my two choices would be either the 6.5-06 or the .338-06.
The .338-06 is just like it sounds, a 30-06 that's necked up to a .338 caliber bullet. It's just got a little more kick than a 30-06 but packs the punch of .338 Win Mag. It's got a great barrel life and the .338 caliber has a wide array of bullet choices.
If I was to re-barrel a long action my two choices would be either the 6.5-06 or the .338-06.
The .338-06 is just like it sounds, a 30-06 that's necked up to a .338 caliber bullet. It's just got a little more kick than a 30-06 but packs the punch of .338 Win Mag. It's got a great barrel life and the .338 caliber has a wide array of bullet choices.