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 October 1, 1964, who was first employed by another participating employer from March 1, 1931, until March 31, 1943, and who was again employed by the same participating employer from April 4, 1949, until February 29, 1956, shall upon retirement be entitled to receive prior service credit for said employment prior to January 1, 1962. The prior service benefit shall be computed by using a prior service annual salary of three thousand three hundred sixty dollars ($3,360).