From a durability standpoint, any pack I have ever had with the stitched on shoulder strap buckles at the bottom has failed. A far more durable option is to run a piece of strap down the centerline of the shoulder harness, locking the buckles in a loop and folding it back under 2-3″ as it is stitched. The little bar tacks have a way of destroying the fabric in the area and causing it to stretch unnatuaraly (ie localized stretching around the bar stitches.)
People wear packs differently. What looks a bit short might be comfortable for him. A lot depends on the back arch, hip arch, shoulder slope, chest dimensions, etc. For the first 20 years or so of packpacking, I carried a 20# base load on my shoulders, only relenting, grudgingly, to go with a strong hip belt after I had a back injury. The hip belt relieved most of the load on my back/neck/shoulders allowing me to continue to get out.