Jeff, it's not just pull you have to worry about, but drop at comb and heel as well. Is he of average height, 5'10" to 6'? If so, you could make the rifle to average dimensions. I'm 5'11", and like a pull of 13 5/8". Drop depends on the type of gun to some degree, as well as the build of the shooter - a strickly offhand gun has more drop than a bench gun, a heavy caliber has less drop (generally) than a light caliber. Barring measuring a gun that fits him well, it will be difficult to make a gun that fits him without having him measured.