I have a .270 and .30-06 and both guns, with proper recoil pads, are not bad for recoil. If he has not had much practice with any centerfire rifle, i would get a nice Sims Laboratory recoil pad. They claim about 50% reduction in recoil.
Alternatively, IMHO the 7mm-08 is almost as good balistically as the .270 (go to the Federal cartridge site and compare balistics) and has less recoil than the latter caliber. I also have a .308, which is similar balistically to the .30-06, but has considerably less recoil. After porting the barrel of the '06 and installing a good recoil pad, however, the difference in recoil between the 308 and '06 is not noticeable.
Thus, it depends partly on your sons sensitivity to recoil and your willingness to purchase additional features that tame recoil, if necessary.
Good luck!