Is there any head in the surefire range that could fit into the A2 body? I would like a powerful LED for the A2, that way I get the best of both world.
Nope. I just tried swapping the A2 head with the L2 head and KL1. Different threading. And it's smaller than a C-series light so those bezels won't fit either. So... nothing at all will fit.
If you want a light very similar to the A2 but in LED form, you aught to look into either the L2 or the K2 Kroma. The L2 has a floodier beam so does not throw as well, but is brighter, and the K2 is a bit bigger, but throws well and has multiple colors as well as a high and low white beam.