Sumner - thanks for the data but how long will it take the human body to become aclimatised to that altitude? If the Brits ever go and I am involved, we will invite you to join the attempt - bringing oxygen bottles with you!
Joe - altitude was a small part of my suggestion that Bonneville is not at the top of some peoples lists. It does not offer 12 (safe) miles of consistent surface for two way running. What is your meaning of a "proper course"?
Inspite of large supercharged aero engines and gas turbines being used the holder of the FIA record three cars ago was normally aspirated. Its record speed of 409 mph is a target in its own right and a fraction below the FIA supercharged class record (reciprocating otto cycle motors).
As far as I know the British team, using the Rolls Royce power claim method - without figures being given, will have "adequate power, sir" for the job being undertaken.