Re: couple questions (thanks in advance)
The 308 can be redone in any standard boltface round in a short action. Options include 6BR and its offspring, .243 Win, 6mm Rem, 260 Rem, 7-08, 308 again, 6.5x47 Lapua or 6-6.5 Lapua and many many many more.
For the 300WM, I would say stay on with it. You can switch to a 30-338WM which should get you a little more barrel life without really giving anything up. This is basically a 308 Norma Mag. You can go with 7mm Rem Mag, 264 Win Mag or any of the STW family. You can also go with a WSM or RSAUM round with a little action modifications. That would also allow you to go for a little more umph with the shortmags as you could seat the bullets out further increasing effective case capacity. Other viable options for LR hunting include Kirby's Allen Mags based on RUM cases or Dakota based mags.