Great read, thank you for posting. There is something to be said for the difficult yet effective head shot.
I like to use bad guy targets to practice a vertical string of 3-5 shots starting from the abdomen and working up to the head, pretty much riding the recoil upwards, essentially just pointing the bullets in a line, and walking them to the head. I do this from a fast draw hip shooting stance right up close, while charging the targets, as well as while running side to side which is by far the hardest. Whether or not that type of practice would apply well to this or a similar situation, I consider myself lucky not to have to know from experience. But I've never heard a strategy that I feel would work better to practice.
2 other thoughts from a veteran I respect a lot who posts on another forum.
"When in doubt, empty the magazine"
"Don't stop shooting until you see brains"