Hey whats wrong with center?
Any who Simon, I was never a QB but played center for 4 years and I can tell you one thing, the QB has to be a leader. He has to be the toughest guy on the field. He is the guy that the other 10 players are going to lean on when the sh-t hits the fan.
As far as fundamentals go, do something that 90% of the coaches never do, teach him to read a Defense. That in itself will make up for any physical shortcoming of any QB. Another is footwork, teach him how to shuffle his feet, also to run with the ball and be ready to throw at anytime. Coaches love that sh-t.
He probably already knows how to throw it, but that's not a perfect science. It's like a golf swing it doesn't have to be perfect just work.