FP,
FAA High Performance is specifically for piston powered aircraft (it is not relevant to turbojet aircraft as they all have a type rating requirement and don't have engines measured in horsepower output.).
In the FAA world anything with over 6000lb payload or 20 passenger capacity must be a part 125 operation (or 121 or 135 if AOC) and these operations need a CPL and certain minimum hours - which would explain JT's Second In Command limitation on the 707.