The GMH code for the front subframe, under front fenders and body wheelhouse was S113 Black which is just the slops black. Many use GMH black from paint suppliers. I reckon you are pretty much on the mark with the underbody, the wheelhouses on teh body would be painted in S113 to cover all that, the front inner guards underneath shouldn't have got overspray as the front panels were painted with but off the car in the body plant (except Elizabeth, not sure where they did their front panels but it was in the assembly plant area).

Tailshaft for a 6cyl HQ short wheelbase (sedan or coupe) is black. Not sure about all the mid wheelbase bodies (wagon, ute, van and Statesman) or the long wheelbase (cab-chassis).