Nice Idea, but you will have to be careful not to make it look "Mechanicum" or possibly the Iron Hands.
I have always liked this colour Scheme on the front of Space Crusade.
If you could adapt this one, and maybe add some Black and white check patterns in the Old Rogue Trader Style it would look somewhere close to awesome.
Painting, I would Prime in Autoprimer e.g. Grey. I would then paint him Deneb Stone, wash it with something like Devlan Mud and then paint up in layers of lighter whites and then highlight with skull white.
For the Black I would go with a Charcoal Colour and then you can darker/shade area's with Chaos black and then highlight with a lighter colour such as Astronmican Grey.
The Advantage of Black and White, is you can literally paint the eyes etc, any colour and it won't look bad.