You can not get through a neurosurgery residency without doing a significant amount of spine. End of story.
In practice, you will not be able to make $200k/year doing only cranial work, unless it's trauma. Everybody enjoys the craniotomies. That is why most of us went in to neurosurgery. In practices, people do not often pass on craniotomies. Starting out in practice, no reputation, and passing on spine, you will not have the volume nor the referrals to make $200k/year or build a reputation to get referrals.