Putting aside the Lucas Prequels, what is your alternative conception of the Old Republic-era Jedi Order? Below I will break this question down into a series of key points. Elaborating on these points will prove crucial to rewriting PT as it is the Jedi Order which must be unraveled and destroyed to make way for the story of the OT.
How many Jedi Knights exist in the galaxy?
What is the basis of Force-sensitivity (innate or acquired)?
What proportion of Force-potentials are in the Jedi Order?
By what process does a non-aligned Force-sensitive become a Jedi Knight?
What sort of distinction exists between Jedi Knights and Masters?
What other Force-sensitive organizations exist?
Do Jedi Knights work alone or do they collaborate? How centralized are they?
Are the Jedi bound to any dress or behavioral code?
Where is a Jedi based? As in, where does s/he spend time when not on peacekeeping missions?