Phenom, I've seen some other temple photos and models with the head/rattles reversed from mine also and it makes logical sense that if the builders are the same group as at Chichen Itza the style would be the same. One thing I've learned about that place is that there were a few groups who used the site and had a hand in the structures there.

I think what really changed my mind about flipping their position was Chan's photo. It just looked to me from that picture that there was a snake head sticking out the side and that it was at the top of the structure. The photo is in this thread. Hope this helps!