For parcels within the blocks bounded by West 50th Street, Tenth Avenue, West 56th Street and Eleventh Avenue, within a general large-scale development that occupies zoning lots on more than one block, the City Planning Commission may permit the modification of open space required pursuant to Section 23-15 (Open Space and Floor Area Regulations in R6 Through R10 Districts) as part of a special permit, pursuant to Section 74-743 (Special provisions for bulk modification), provided the Commission finds that:

(a)        the amount of open space provided is sufficient to meet the needs of the residents of the general large-scale development; and

(b)        such modification results in improved site planning.