The factory loadings for a 1962, and 1958 cartridge are going to be conservative compared to rifles for a cartridge from about 2005. Old rifles, customs often made with even older actions.
The 300wsm is really close to 308nm. I can get the 308nm to the bottom of 300wm factory ammo performance with handloads. I'm not much of a drop tube and put the loading block on a running jigsaw guy. I find a accurate load, if more performance is needed use a different rifle. Really though comparing max handloads to bargain factory ammo from a more powerful cartridge? Apples and oranges.
Back to original posted question. Either rifle caliber is fine. The 7mag for deer option elk, moose; 338wm for larger....option deer.