68 Manual Steering Box

[SS427]

Correct on the natural finish on the spanner nut.
Cast iron top will be the same as the housing. I personally have only ever seen natural cast iron housings and not paint black but others argue that they were painted black.
Bolts are black phosphate (Parkerizing)
As for the pitman and stub shaft, I polished them with emery cloth and then use copper paint to replicate the copper plating. As for the nuts, I have seen them both black phosphate and a dark green color similar to what you see on the aspirator tubes.

Understand, these are what I have encountered over the years and are just opinions. Others may vary.