Been very happy with my 300Wby. Suggest trying the 155gr Amax in a 1 in 12 twist or similar. This combo flies way flatter and drifts less then expected. Much better then the 168gr (amax, nosler J4, ballistic tips) I have tried in my rifle. My muzzle vel is 3200 to 3250fps with the 155 and 3100fps with the 168's.
For a plinking/varmint load, I am sold on the 155 Amax bullets. Shot this combo to 1800m (1960yds) a couple of weeks back. Bullet stays stable.
Look at some recent reloading manuals (Nosler #5) and you will find that there is not that much difference in performance between the Rem and STW. The Nosler manual actually lists the same vel for both.
From a long barrel rig, the STW will shine but in a 26" barrel, wouldn't bother. Lots of barrel wear, recoil, noise, component consumptions and 100 to 150fps more...maybe.
The 7 Dakota
would be a good choice. Maybe a shortened ultra mag. These would be the same as the Rem without the belt. The short magnums (Win and Rem) won't be able to perform like the reg. 7mm Mag when using heavier bullets.