A quality 220 gr 30.06 bullet to the kill zone will certainly kill anything other larger cartridges will but a 280 fr Swift Aframe in a 35 Whelen should have more smash with a larger diameter and decent penetration with a SD over .300.

I maybe picking nits and dead is dead but--

Methinks I would want the Whelen for frontal area smack and penetration.Its only flies would be if it couldn't be pushed fast enough and approx. 2400 fps for 280 gr should work fine !!!