Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 to the contrary, an employee who became a member of the Kansas public employees retirement system on March 1, 1963, who was first employed by a participating employer from May 12, 1952, through May 29, 1956, and was employed by the same participating employer again from December 1, 1956, through September 15, 1961, shall upon retirement be entitled to receive prior service credit for all such employment prior to January 1, 1962. The prior service benefit for such member shall be computed by using a prior service annual salary of four thousand eight hundred forty dollars ($4,840).