The provisions set forth in Sections 52-53 (Buildings or Other Structures in All Districts) and 52-54 (Buildings Designed for Residential Use in Residence Districts) shall be modified to allow all buildings containing non-conforming uses to be reconstructed, provided that:

(a)        for non-conforming single- and two-family residences in Residence Districts and Commercial Districts, except C8 Districts, such reconstruction may exceed 75 percent of the total floor area of the building;

(b)        for non-conforming single- and two-family residences in C8 Districts or Manufacturing Districts, such reconstruction may exceed 75 percent of the total floor area of the building provided that 25 percent or more of the aggregate length of the block frontage on both sides of the street facing each other is occupied by zoning lots containing residential or community facility uses;

(c)        for all other buildings with non-conforming uses, the extent of reconstructed floor area shall not exceed 75 percent of the total floor area of the building.