RE: 308 or 300 win mag
Define "long range". And what do you plan to use the rifle for?
Out to 300 yards, my choice would be the .308 Win. for both punching paper and hunting deer or elk. If you're just going to punch paper then the .308 would also get the nod for anything less than 500 yards. The .308 is known for great accuracy and isn't too finicky if you handload, and the recoil and cost will be much more tolerable if you like to shoot a lot.
For bigger game (elk+) beyond 300 yards, I'd probably go with the .300 Win Mag, or .300 WSM if I were to stick with a .30 caliber. The down side is that if you like to target shoot, the magnums will punish your shoulder and wallet a lot more than the .308 will.
Mike