Hi nice work, I always think of

as resembling a 70's style Dr Who type monster...so an Actor in a costume makes a lot of sense to me personally, kind of like a behind the scenes photo.
However, if you really want to keep it real to the

background story may I suggest a bunch of wiring inside the helmet..or something that looks like Masker-tron or the Fembots, with the human masks removed, from the 70's Bionic Man T.V. shows?
Or if you want modern how about a Terminator type head..or even a

under the helmet?