This proposal is unethical. To show why, consider Christiaan Barnard, who did the first heart transplant.
His first operation failed. So did his next. But his first 50+ attempts were on dogs, and were eventually successful. Only then did he do a heart transplant on a person. (Yes, I find it easier to kill dogs to save the lives of humans than to kill humans for the same reason. Don't mistake that for thinking I find it easy to kill dogs.) That operation was a success, though the patient died 18 days later due to pneumonia as he was taking immunosuppressive drugs.
Where are the dogs with a successful head transplant? Or rats or monkeys or other mammal?
One of the links a couple of years ago was to https://news.ycombinator.com/item?id=5972171 :
> Jerry Silver, a colleague of White’s [who did monkey head/body transplant experiments in the 1970s] and the neurosurgeon behind the rat spinal cord experiment [where a rat's severed head was reconnected with its own body], objects to the entire notion of a human head/body transplant. “It’s complete fantasy,” he said in an interview with CBS News. Reminiscing about the psychic torture that he believes White’s original monkey patient suffered, he added, “I remember that the head would wake up, the facial expressions looked like terrible pain and confusion and anxiety.” He dismissed Canavero’s theory as “bad science.” Given how controversial the monkey experiment itself was, it’s highly likely that Silver is one of many.
I like jessriedel's comment in the HN discussion from 647 days ago at https://news.ycombinator.com/item?id=5972171 :
> There are plenty of crazy doctors out there who make nutzo claims not backed up by evidence in their field. One neuroscientist chosen at random is probably reasonable and competent, but a neuroscientist chosen conditional on publishing an astounding claim that isn't shared by any of his colleagues is almost certain to be cray.