My normal advice would begin by asking what sport or sports he likes best and is good at but it sounds like he hasn't tried many yet? As you've mentioned, a large HS in CA. is going to have competitive teams in all the major sports so there may be an issue of making the team.
It's interesting that he has a background already in dance. One of the best athletes we ever saw in HS, (big football and track star, seriously fast), went on to be a big ballet star, top man in a prestigious company. Those guys are real athletes for sure.
One thing I would consider, unless my son was an absolute Sherman tank, is the potential for injuries in contact sports like football. I think that FB is a great team sport and I love it but the injuries these days even at the HS level are something to really think about.
Baseball is a great game, (my favorite spectator sport), but if he has not been playing competitively since childhood there is no way he is going to play at a big HS. Same goes for many other sports.
I'd encourage him to start practicing some sports that he might like and have a chance of really playing at this school, he sounds athletically gifted enough.
