With everything I have done so far. I don't think that you will be able to use FSC as an Autopilot for the 707. The important Heading, VOR (NAV) and Approach modes are control via the 3D VC A/P. Nothing I have tried changes that. You can use either the Bendix-King Radio A/P, B737-800 or Airbus A321 A/P. The B747-400 only uses the numerals for the A/P on the VC panel texture and so can't be used in an easy manner.

Mark