Here's what the Anderson/Moment book has to say on the subject:
"On two-tone cars, the secondary coat was sprayed over the primary coat in the area below and behind the pressed-in swage line on the fenders and doors. In all cases where the car was painted two-tone at the factory, only the flat portion of the lower panel was painted the second color, and the upper body color extended down over the bevel to meet it. (It should be noted that cars were frequently painted the second color by the retail dealer at the owner's request, so "original" cars may be found with a different break point.) The second color was not painted on the inside faces of the doors. Also, it was not painted across the lower portion of the rear shroud."
Cheers,
John