Billboard Gui only visible to someone at a certain distance? [SOLVED]

First of all I know I could find the magnitude between the players etc... But the Billboard Gui is to display the players level above their heads and the script it self that controls that is inside every players head.

What would be the easiest way about going around the problem of each player individually scanning ever other players head to see if they're within distance? Or if that is the case then would it be a long winded process?

Thanks, Cuvette

I mean, I am not a pro-scripter by any means nor do I know how it would happen with a player, but if you wanted it to show for a certain spot just have an invisible block and when they touch it the bil would be cloned into the part you want it to show.