here's what i did
(replacing the helmed horror with the air revenant model from wow)
i deleted all of the faces of the head(helmed horror) mesh but kept one face,
then i attached it to the revenant's head mesh, then deleted that one face of the helm horror's head mesh
i did the same to the rest of the meshes and applied the revenant's texture to them
and i did all this using 3ds max
the download links for the model and pdf(how i did the head) are here: