Within the Special Downtown Jamaica District, for any zoning lot in a C8-1 District prior to September 10, 2007, the provisions of paragraph (b) of Section 52-332 (Other buildings or structures in Residence Districts) and the provisions of paragraph (b) of Section 52-35 (Manufacturing or Related Uses in Commercial Districts) shall be modified as follows: A non-conforming use listed in Use Group 16 may not be changed to a use listed in Use Group 17.