...between the 35 Whelen, and the 350 Rem mag, I'd go for the Whelen. Brass is everywhere ( '06, 270, 280, etc..) and does not have a belt on it... The difference in a long and short action is minimal.. I'll bet most people can't tell the difference. Also, I think with the 350 mag, if you load heavier bullets, they tend to encroach on your powder capacity. I could be wrong about this, but I think I have read people complaining about it. The Whelen (I have one) is just a dandy cartridge. I shoot a 225gr bullet at about 2700fps, and the recoil isn't as bad as I thought it would be. More than an '06, less than a .338 Win mag...
Ballistically, I think it's a dead heat between the 338-06 and the 35 Whelen... but I just like the extra 20thousandths of diameter... bigger is better. Actually the 375 Hawk/Scovill might be the perfect big game round out to 200yds.... I'm tempted to try one of those.... and I do have a couple of extra mauser actions sitting around... hmmm

"Progress, far from consisting in change, depends on retentiveness..those who cannot remember the past are condemned to repeat it." Santayana