for the neck, yes use leather, with the hard helmet like normal, but get it all flowing, use the leather up to that strip in the middle/top of the head, or better yet have that be leather too, and have the side connected only to that for a better flow down tothe shoulders.
Is this armor in any other game other than ST galaxies? If so, I might be able to rip out the mesh, or at least get really good reference pics straight from the game engine.
In the next couple weeks, I could probably model out a rough idea or two. Just gotta get through with HS graduation.