Grey Knights commission

I think that I have picked up my first Grey Knights commission with a friend of mine dropping his dreadnought on my floor and saying "oops," as it breaks into 5 pieces. I gotta wonder if this was an accident because he may have known that I would pick up the pieces and put it back together and paint it for him. This is going to be a speed paint job and lucky for me, they are already painted black with details picked out. Below is a picture of the original grey knight color, which was black.
I have another grey knight army that I was going to speed paint for the club to auction in June at our tournament.