it sounds like you have the right idea for your son. i don't know if you are looking at bolt action only, but i would also throw a marlin 336 30-30 into consideration. i bought one a few years ago when i turned 18 and love it. the 30-30 is a great all-around cartridge, and the 336 is a very well-known rifle, with kick very similar to your sons 870. the size of the rifle will probably fit him pretty good too. good luck with whatever you choose.