Engine bay aluminium panelling is natural unpainted aluminium. If a 2.6, fibreglass foot boxes were black. Boot interior sprayed silver. Door hinges body colour. Chassis metalwork black. Can't remember about bonnet underside or wheel arches, others should be able to help.
A copy of "Original AC Ace and Cobra" by Rinsey Mills is well worth the investment, not easy to find though.
For a fraction of the book price you could join the club and talk to real AC people and look at their cars.