CONGRATULATIONS !!! Looks like your son is headed in the right direction.
I would suggest he play some 14.1 Straight Pool. It will help his position play and also improve his pattern play. Speed control drills will also help.
KEEP STROKING ... STRAIGHT !!!
He does ask to play straight pool once in a while but I am not very good at it (my high run is barely over 30 balls) and he gets mad at it quickly once he realizes he is not that good at it and quits LOL. We played a few games and soon as I would be ahead by a rack or two he wants to change to something else.