Sections 462C.01 to 462C.07 do not impair or otherwise affect the validity or provisions for the security of any obligations issued or agreements made pursuant to law before June 2, 1979. Sections 462C.01 to 462C.07 do not preclude or affect or limit the institution or financing or character of a housing program, project or development permitted for any city by any special law in effect on June 2, 1979, except that: (a) section 462C.03 is applicable to any program undertaken pursuant to a special law adopted after January 1, 1979, (b) no such city or agency thereof may issue obligations after January 1, 1980, for the purpose of financing a housing program or development of any kind referred to in sections 462C.01 to 462C.05, unless its plan therefor has previously been reviewed by the appropriate reviewing body and its program has been reviewed and approved by the agency; and all such obligations issued by such cities after January 1, 1980, shall be subject to the limitations set forth in sections 462C.01 to 462C.07.