It is definitely a challenge to play on the line at that weight, and proper technique will certainly give him the best chance to succeed, but if I were to give one piece of advice based on our experience this past year, it would be to get him into the weight room for strength training as much as possible (of course consult with your pediatrician, trainer, etc. on what is the best/safest program for your son.)
My kid is not the largest, but he busts his ass in the weight room and is probably top 5-8 strongest on the team. It helps so much for two important things:
1. Cuts way down on injuries to have more core and arm/leg strength.
2. Gives you an upper hand over larger kids who just rely on their size to bully smaller opponents.
Last game a player on the other team who outweighs my boy by like 45 lbs tried to cheap shot him after a play was dead by jumping him from behind. My kid just grabbed him, flipped him completely over his head and body-slammed the poor SOB. Didn't mess with him after that! 😁