Need Help with head-hacking.

No, I am not requesting a head-hack tutorial. I have been attempting to head-hack Squiddy’s Desmond Miles rag-doll head onto the human hunter player model. I’m so close, but the model comes out, well… deformed:

Squiddy has helped me through all of my problems so far, but for this one, he drew a blank. Therefore, I’m asking if anyone else has an answer to this.