I have never shot a .358, but I have shot a .35 Whelen, and I agree - the .350 Rem Mag is very close to a Whelen - which is quite a bit. I forgot what loads I was using, but I think they were factor 200 grainers. That Guide gun comes with a nice recoil pad, whereas the Whelen that I shot didn't. Still, the 350 Rem mag hit you with some authority. I used it on a hog hunt - great nitch rifle for that scenario.
Zachary