Effective July 1, 1969, the monthly benefits payable to or on account of any member who retired from service prior to July 1, 1964 and who, had he remained in service thereafter would have been a Class Two member, shall be recalculated in accordance with the provisions of the System applicable to Class Two members retired on or after July 1, 1964, including any adjustment thereto which would be applicable under § 9-1-1740. The benefit so determined shall be compared with the monthly benefit payable to or on account of the member under the System as in effect on June 30, 1969 inclusive of the supplemental allowances payable under the provisions of §§ 9-1-1910 and 9-1-1920, as amended, effective July 1, 1969, and § 9-1-1930 and the increase, if any, in the monthly benefit shall be paid from the general fund of the State.