The Oxford Museum. I was going to ask, but they beat me to it. I've seen some shrunken heads in a Jivaro display at the Cleveland Museum once, but they only had a few. That looks like one hell of a collection.
My shrunken head is for sale. It's clearly the real deal; hairs in the nostrils and ears. Bought it about 8 years ago. It's around 150 years old. Comes in a nice bell jar with wooden bottom.