Re: multi purpose 308
I would go with a 24" to help with a good velocity. You want at 2650fps with your 175's. Other than that, sounds like a good set up. I have a Savage Mod 12 action with a 28" barrel on it. The thing just flat out shoots. It's crazy accurate. I have B&C Medalist A2 stock on mine. Works good, but would have to say my next stock will be a stockade. For your subs, I would go with a 180-220 grain round nose.
"Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.  But small is the gate and narrow the road that leads to life, and only a few find it.
If you find your self in a fair fight, your tactics suck!- Marine 1st Sergeant Jim Ryfinger
Friends don't let friends develop canonitis!
arguing over the internet is like the special Olympics....even if you win, you are still...special!