Eric welcome to the HSBBW. Work to get as fast as you can , as quick as you can , as athletic as you can be. Thats all you can really do. Speed , quickness , athletic ability is important. How important his 60 is will be determined by what posistion he plays , does he hit for power , is he a very good base runner , etc.
Most kids your sons size are not mif or outfielders. I would assume pitcher , 1B or catcher? He wont have to be a burner but he cant be a base clogger either. And of course he will need to hit for power. Good luck.