SKSBoy,
Re-think the use of a suppressor on a 30-06. Granted your going to loose some of the boom, but you will still have the crack due to the round leaving the barrel a sonic speed. The real purpose for a suppressed High power rifle is disguise the report and location of the origin of the shooter.
Here is a example:
Shooter is at point A. He shoots to point B. The spotter is off to the side of point A,B.
As the round goes down range, making a lot of noise(sonic boom), the spotter hears the round. But, due to the muffled report of the gun, and the noise coming from the round. The spotter with think that the shot began at a point in between point A and C, because that is where he first heard the round.
If you are going for a quiet rifle, then you will have to get the bullet to leave the barrel at sub-sonic speed. In the 308, there are brass cases that have been produced to allow you to use reduced loads(low volume). If you just try to reduce the powder in a standard 30-06 case to bring it down to sub-sonic speed, you stand a good chance of blowing up the gun. By under loading a case, the primer flash can reach the front and the rear of the powder and can create a pressure wave spike due to the powder burning at a uncontrolled rate or double rate.
I don't mean to piss on your parade, but if your going to suppress a firearm, then go with a 9mm or 22. Both rounds are offered in a subsonic round that won't cost a lot of money.
As for my choice, Ruger mark II with integrated suppressor. All you hear is the casings tingling off the concrete floor and the bullet smacking the target.