When screwing on a barrel, no more than 30 pounds torque is needed - this makes changing barrels easy.

I would leave the .308 barrel as-chambered. Iseriously doubt anyone is able to see the difference between the .308 and .30/06 on game. The .308 will probably chamber from the CZ magazine just fine. If it doesn't, THEN, it's time to think about a re-chamber.

The .30/06 case is not shaped the same as a 9.3x62 as the '06 has a LOT more taper. The 9.3x62 is very much closer to a .30/06Ackley Improved case. The .308's profile is much closer and is why it will probably chamber just fine.

Although I've seen some scematics on the 9.3x62 showing a .450" to .451" shoulder, 2 different 9.3x62 factory made and chambered rifles show a .454" shoulder, which is Ackley Standard for the improved '06 case.

Something no one has touched on, is that due to the fatter shoulder of the .308, it is probably not possible to re-chamber to '06 without the resulting chamber having a double shoulder. The first shoulder will be about .4" lower than the real one. The mid-case shoulder will be .455" and the '06 shoulder of .441" - quite a visual difference. This is another reason to consider the '06IMP chamber so the case's sides will be straight, without another step. Dies of course cost more.

The '06IMP will give enough of a boost to the '06 to make the chamber worthwhile, compared to a standard '06 and .308 comparrison.