I would let him use the 270 but it is not a light recoiler.It is a the old remington Spotsman 78, with the ugly white camo stock and it only has 20 in barrel (I got it cheap cause someone cut the Barrel off).It has a terible muzzle blast.
I do have a 7mm-08 in a remington Mtn. Rifle (I forgot about that one)how about that 140 gr slugs it is almost a twin to the 280.What ya think will it kick him to hard?