I'd leave this one alone. The plate looks bad and there's nothing about it that makes me think its anything other than a parts helmet or out and out fake, especially that nice brass wood screw holding the chin scales together.... I can't tell what in the world is holding the chin scales on at the side. Also the neck guard looks dicey. To me, the plate looks like a fake, the detail is so mushy and to me it looks like it was cast or similar because there seems to be a crease (as from a double mold pour) on some of the neck feathers... could just be a bad photo, but the plate still looks bad to me.
Ron