[asid61]

If you have not done it before, I would recommend against it. Your drivetrain alone can score you many points, and an inoperational one could shut you down this game.
I know many teams have done 24t 15mm before with success, but I don't know how many used direct C-C distance or how much they added/subtracted to the distance.
What do you mean by "accurately drilling"? I would definitely not do this with a drill press or something.