first off... no kid at the age of 14 will have messed up growth from lifting if he's taught proper form along with being coached properly. I coach highschool kids anywhere from 14 to 18 with zero problems that compete in highschool powerlifting and sports. Just hammer down the foundations and techniques and there will be no problem with him powerlifting.
Both you guys can work on a modified westside routine without the optional additional work and make strength and size gains just fine as long as you're eating and supplementing right. If yo'ure just getting into this or it's a MAJOR routine change..i'd start taking something like ETS from ALN or another recovery product to help keep the DOMS that are sure to show up away and slowing you down, especially in the beginning. All my training clients now are taking ETS the day they signup to work with me and i've yet to have one person complain about muscle soreness even after working through some tougher stuff!
