Cool! Thanks for the opinions, guys! That's the kind of info I was looking for.
I figured the original is yak or possibly yak and horse, or yak, horse and wool.
Yes, I considered that adding hair may not look right and that while the original looks cool under low lighting, a replica with hair may just look really off.
I have worked with human hair and some sort of synthetic, maybe it was the Kankeon you're talking about. I haired up my Planet of the Apes gorilla solidier, using a wig on top, which covered the back, and then I did the beard and side areas, and forehead, blending into the wig. Turned out pretty good, but I hated the synthetic hair and wished I had used horse hair as they did with the originals.
The bust hasn't arrived yet, so I guess how it looks when it comes will be the deciding factor of what I end up doing, if anything.
This is my favorite werewolf movie and I wanted this bust before I even knew one existed so I want it looking as good as possible.
Here's an example I found of the same sculpt with molded hair ground down and new hair added. I'm not crazy about the look. As a generic werewolf, it looks okay, and the detail work on the mouth is excellent, but overall the thing looks nothing like the werewolf from the first movie. The flesh is too light, and the hair too gray. Maybe they were going for one of the sequel werewolves. Don't know.