Peter found my photoshop comparison technique rather interesting in person. He'll probably be popping on here or his blog with his take on this shortly.
All I have to say is multiple layers and transparencies are your best friend when comparing works.
This is where I started.
This is where I'm currently at.
So I need to get the details like lip scales and teeth back onto the head.
I'm also toren as to whether go with the new age concept of Theropod lips covering up the teeth.