The one piece of advice I have for this situation is don't rely on commercial airlines for this. With the length of time needed to get to St. Louis from his home and the diminishing returns on time available for transplant, if he's not going to move to St. Louis to wait for the transplant (understandable), then he needs to have access to an on call private jet, no matter the cost. Relying on commercial airline schedules is going to be hard with limited flights and this being time sensitive.
A coworker's husband is currently waiting on a transplant from St. Louis and he has not moved there (young child in school, with jobs here and family and support system here, etc). But the coworker has priority access to our company's planes whenever needed and we are only a 1 hour flight from St. Louis.
No matter what, best of luck to your friend.