(1) The agency may insure mortgages containing provisions for varying rates of amortization corresponding to anticipated variations in family income to the extent such mortgages: Have promise for expanding housing opportunities or meeting special needs; and
(2) Can be developed to include any safeguards for mortgagors or purchasers that may be necessary to offset special risks of such mortgages.
(3) Graduated payment mortgages insured by the agency pursuant to this section shall comply with the rules and regulations promulgated by the secretary of housing and urban development pursuant to 12 U.S.C. § 1715b and 12 U.S.C. § 1715z-10 [repealed]; provided, that this section shall only be applicable to first mortgages.