Sorry for low quality, used my cell phone. My Pelican case of Oveready goodness.
I don't have a black C2, mine is HA natural but here is how it looks with an Oveready-bored A19 black HA extender. I think a HA head would be less obtrusive then my setup, but in the dark nobody can see the body of the flashlight anyways (is my rational for currently using the natural C2 with a black extender).
Drop ins from L-R are Oveready M2/XML2/DD head, Malkoff M61 on the Z2, Malkoff M60 on the C2, and Oveready Triple XPG2 on the 6P with extender. I like the trade off of shorter length for the increased voltages of running the M60 and Triple XPG2 on 18500s with the A19s. Better runtimes on 2x 18500s compared to using 2x 18340/18650 on the shorter body. The M2 and 6P are on 18650s. All of the above are Oveready-bored to 18mm and have Zero Rez tailswitches.