My 308 is a Punishing Bastard(no brake). I shoot more 223 than anything. I would get a cheap 6gt barrel for practice. Criterion is 300$, headspace it to match your other rifle.
I have a couple of the pro varmint stocks, I like'em. It would be awesome getting a factory 20" in the pro varmint, not that its necessary.
Thanks for posting results.
I run 41.1 of imr 4451. Pretty light. You might want lapua brass for 43grns. I just checked two books online and they don't hit 42grn of h4350(only 60k psi).