VERY cool idea of a costume.
And a mega build for a mega mecha!! Love what you're doing. The complete costume will be magnificent. Dying to see it all done!
I think shortening the bottom jaw a tad would help. Also, the bottom teeth should be set in toward the center a little more. The profile should be a slightly slanted line, like \ instead of a V shape like it is doing now. The snout might be a tad long too, but I think working on the jaw first would be easier and may be all you need to do.