In the case of any individual who is entitled for any month to benefits based upon the primary insurance amounts of two or more insured individuals, one or more of which primary insurance amounts were determined under section 415(a) or (d) of this title as in effect (without regard to the table contained therein) prior to January 1979 and one or more of which primary insurance amounts were determined under section 415(a)(1) or (4) of this title, or section 415(d) of this title , as in effect after December 1978, the total benefits payable to that individual and all other individuals entitled to benefits for that month based upon those primary insurance amounts shall be reduced to an amount equal to the amount determined in accordance with the provisions of paragraph (3)(A)(ii) of this subsection, except that for this purpose the references to subparagraph (A) in the last two sentences of paragraph (3)(A) shall be deemed to be references to paragraph (7).