I'm making a Caesar's Legion sniper character, and I need to know where to find some Caesars armor, preferably the Centurian/Praetorian armor without killing CL and losing rep. Any ideas?

Without killing them yourself, the only reliable way to get their armor is follow a patrol around waiting for its members to die off. I don't believe you will find any with Centurion armor out on patrols til late in the main quest (if ever), and Praetorian armor may only be acquirable by sneak-killing one or possibly doing so in disguise of another faction - successfully doing so will not give you a reputation hit.