Conductors, I'm feeling brave...?

Okay, so it's taken me eight years of conducting Middle School Orchestra to build up the courage, but I am going to take the plunge and set up a full orchestra for next year. My question is, when I add the winds, br, and percussion, how many kids do I put on a part? I have gotten alot of joke responses from colleagues (like "one for every Tums in the bottle"), but no straight answers. I am uming I should stack the winds a little heavier than the br because of projection capabilities, but concrete numbers would be helpful if you can give them. We have a strong program here and I will only be doing this for one piece of our concert program. HELP!!!