A property or project covered by a mortgage insured under the provisions of subsection (d)(3) or (d)(4) shall include five or more family units: Provided, That such units, in the case of a project designed primarily for occupancy by displaced, elderly, or handicapped families, need not, with the approval of the Secretary, contain kitchen facilities, and such projects may include central dining and other shared facilities. The Secretary is authorized to adopt such procedures and requirements as he determines are desirable to assure that the dwelling accommodations provided under this section are available to displaced families. Notwithstanding any provision of this chapter, the Secretary, in order to assist further the provision of housing for low and moderate income families, in his discretion and under such conditions as he may prescribe, may insure a mortgage which meets the requirements of subsection (d)(3) of this section as in effect after June 30, 1961 , or which meets the requirements of subsection (h), (i), or (j) with no premium charge, with a reduced premium charge, or with a premium charge for such period or periods during the time the insurance is in effect as the Secretary may determine, and there is authorized to be appropriated, out of any money in the Treasury not otherwise appropriated, such amounts as may be necessary to reimburse the General Insurance Fund for any net losses in connection with such insurance. Any person who is sixty-two years of age or over, or who is a handicapped person within the meaning of section 1701q 2 of this title, or who is a displaced person, shall be deemed to be a family within the meaning of the terms “family” and “families” as those terms are used in this section. Low- and moderate-income persons who are less than 62 years of age shall be eligible for occupancy of dwelling units in a project financed with a mortgage insured under subsection (d)(3). In any case in which it is determined in accordance with regulations of the Secretary that facilities in existence or under construction on December 31, 1970 , which could appropriately be used for classroom purposes are available in any such property or project and that public schools in the community are overcrowded due in part to the attendance at such schools of residents of the property or project, such facilities may be used for such purposes to the extent permitted in such regulations (without being subject to any of the requirements of the proviso in section 1715k(d)(3)(B)(iv) of this title except the requirement that the project be predominantly residential).