Doesn't the bezel just unscrew like any of the other bezels from Surefire? I just glanced over at our favorite auction site and found at least one Z44 and KM3 replacement bezel with no problem. The 6P should have the same C-size threads that all of the original two cell lights like the original 6P, the C2 and C3, the G2 and G3, etc. have. Lumens Factory even has some C to M adapters that would allow you to use one of their M series Turbo heads. Unfortunately, they are all natural finish, and not black.
You can also check the Modders forum here as well, as well as the WTS (Want To Sell) threads.