(g) “Low and moderate income families and persons” means families and persons who lack the amount of income necessary, as determined by the municipality, to purchase or rehabilitate safe and adequate housing without financial assistance under this chapter. The income limits for families and persons assisted under this chapter shall be established by the municipality, provided such limits shall not be set at a level which is (1) higher than one hundred twenty per cent of the current median family income for a family of four in the Standard Metropolitan Statistical Area, as designated in the federal census, within which the municipality is located or (2) with respect to distressed portions of the municipality, higher than two hundred per cent of the current median family income for a family of four in such Standard Metropolitan Statistical Area and provided further, up to fifteen per cent of the total financial assistance under any housing finance assistance plan may be provided notwithstanding subdivisions (1) and (2) of this subsection upon a finding by the legislative body that a public purpose is served thereby in encouraging the development of a balanced community of all income levels in the urban areas of the municipality;