Notwithstanding the provisions of Kan. Stat. Ann. §§ 74-4913 and 74-4919a to the contrary, an employee who retired under the Kansas public employees retirement system on October 1, 1976, who was first employed by the same participating employer on October 1, 1962, through January 6, 1969, and who was again employed by another participating employer on December 1, 1969, through November 30, 1970, shall on the effective date of this act be entitled to receive prior service credit for such employment on October 1, 1962, through January 6, 1969, and may elect to purchase participating service credit for the period of December 1, 1969, through November 30, 1970, under the provisions of Kan. Stat. Ann. § 74-4919a. The election to purchase participating service credit and payment must be made within six (6) months of the effective date of this act. Any benefits resulting from the purchase of additional participating service credit under this act shall accrue from the first day of the month following receipt of payment for such service credit. The prior service benefit shall be computed by using a prior service annual salary of six thousand three hundred four dollars ($6,304).