Those cars came from the factory with 2 tone paint but the color break was on top of the roof rather than at the belt line. It covered the hood and wrapped around the back of the side windows and over the roof...just things to consider.
Silver and black are going to give you somewhat of a high class luxury look...like a tux. Silver and graphite are more of a techy machined look. Whichever way you go, I would separate them with a colored pinstripe as shown in this rendering of my project:
Good Luck!
Ben