my two cents is late, but here goes:
PERSONALLY, I am all about authenticity when it comes to restorations. My Galaga for example will get the black leather style.
But, IF, and I say IF I were to go for something different that really compliments the overall cab, I would consider WHITE (it would really accent the outline of the cab) or a yellow that matches the yellow in the side-art. (Again, it would accent the outline of the cab, but stay within the existing color scheme).
Blue, I find would just blend in would your sides. (But then black blends in with the front, so... maybe that's not a bad thing).