If you know where you're going to school next year, get in touch with the football team's strength coach and find out what he recommends. As long as you're not going to Penn State, you probably won't go wrong taking that route.
Also, it probably wouldn't be a bad idea to learn the olympic lifts, or at least cleans; those help with the explosive power you'll need for football.
And one thing I wish I'd done back in HS when I was playing O-line (though it was at about 100 pounds less than you are), which I assume you do at your size . . . push around some trucks, SUVs, or minivans. Just get someone to put the vehicle and neutral adn steer; it's a hell of workout, and simulates pushing around heavy ass linemen better than anything I can think of off the top of my head.