Why not just cut the buttstock down to the LOP you need and install recoil pad? I did that on a Marlin 1894 357mag. for my son. Itis the one that has the birch stock. No way I was cutting down my own 1894c with walnut stock.

Once again the .260 Remington gets overlooked.

IMO it is the perfect balance between a 243 and 7mm-08 and is inherently more accurate and carries energy downrange better than either one and has less recoil as well. My 12 year old daughters have killed tons of deer and hogs with my 260.

Real friendly - .243, 6mm Rem, .243 WSSM, .257 Roberts, 6.5 Swede

Fairly friendly - 25/06, .260, 30-30, 7mm/08, 8 X 57 Mauser

Still friendly or able to be made friendly - 35 Remington, 300 Savage, 7 X 57, and more

But anyone of the above calibers can kick your butt in a lightweight rifle with a poorly fitted stock. In a normal weight rifle that is fitted to the shooter properly with a decent recoil pad and proper technique all of the above (and many more) calibers can be tame even at the bench

Get him either a 243 win., 260 rem., 280 rem., or a CZ6.5x55 swedish mauser. I would get the 6.5, i have one for big game hunting and its one of my top rifles. in fact is is. if ur son hits a deer a little to far up, behind, or forward i promise that you guyz will still have to check one in. and he wont go far.