1969 M code Barracuda

Hello to all, im helping a friend button up some details on his M code. One question is his original mastercylinder , lid, lid hold down bracket and the bolt. Does anyone know for sure what finishes are correct for these items? the car has 4 manual drum brakes and of course a 440.... what is left natural? what is plated? what type /color plating? any help from the experts would be appreciated... thanks Mad dog