Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4911 and 74-4913 to the contrary, an employee of a participating employer who was first employed by said employer in the month of June, 1931 until March 19, 1948, and who was again employed January 6, 1964, and who is employed by a participating employer on the effective date of this act, shall be an eligible member of the Kansas public employees retirement system as of February 1, 1964, upon the payment of appropriate employer and employee contributions, and shall be entitled to receive participating service credit for employment with said participating employer from date of membership until attainment of age seventy (70) and shall receive prior service credit for all employment with said employer prior to January 1, 1962. A prior service benefit shall be computed by using the prior service salary of four thousand one hundred forty dollars ($4,140).