Within 100 feet of Mermaid Avenue and within 100 feet of Stillwell Avenue, except within 100 feet of Surf Avenue, all portions of a building or other structure shall comply with the height and setback regulations of the underlying district and the street wall location provisions of paragraph (a) Section 35-631 shall apply, except that the street wall of a building shall be located on the street line and rise to a minimum height of 40 feet or the height of the building, whichever is less.