This is the only reason I haven't signed up.

What I want to do is sign up for neuropreservation and donate any organs and tissues from the neck down, but as far as I can tell that's not even remotely feasible. Alcor's procedure involves cooling the whole body to 0C and injecting the cryoprotectant before removing the head (and I can understand why perfusion would be a lot easier while the head is still attached). Also, I think it's doubtful that the cryonics team and the transplant team would coordinate with each other effectively, even if there were no technical obstacles.