The underlying height and setback regulations shall apply, except that the front wall of any building shall be coincident with the street line for a minimum height above curb level of 16 feet and, in a C2-4 District mapped within an R6A District, a maximum height above curb level of 50 feet or, in a C2-4 District mapped within an R7A District, a maximum height above curb level of 60 feet.