Any employee of a participating employer who is a member of the Kansas public employees retirement system, who was previously employed in a teaching position with a public school system of another state, in a foreign teaching service in an overseas dependents’ school, in a recognized teacher exchange program or in any program where a teacher is chosen by the Kansas department of education to teach in a foreign country and which service otherwise meets the requirements of an employee as prescribed in subsection (14) of Kan. Stat. Ann. §§ 74-4902 or subsection (4) of Kan. Stat. Ann. §§ 74-4932 and amendments thereto may elect to purchase service for such out-of-state public school or overseas teaching employment. At the election of the member, the benefit for each such year of employment shall be equal to either 1% or 1.75% of the final average salary of any such member. For any member who elected to purchase service credit as provided in this section prior to the effective date of this act at the 1% rate, such member may elect to purchase such service credit at an additional amount of .75% of final average salary of such member in a lump-sum amount as otherwise provided in this subsection. Subject to the provisions of Kan. Stat. Ann. § 74-49,123 and amendments thereto, such member may purchase such service credit by making application therefor prior to date of retirement at an additional rate of contribution in addition to the employee’s rate of contribution as provided in Kan. Stat. Ann. §§ 74-4919 and amendments thereto, based upon the member’s attained age at the time of purchase and using actuarial assumptions and tables in use by the retirement system at the time of such purchase. Such additional rate of contribution shall commence at the beginning of the quarter following such election and shall remain in effect until all quarters of such service have been purchased. Subject to the provisions of Kan. Stat. Ann. § 74-49,123 and amendments thereto, any such member may purchase such service credit as described in this section by electing to effect such purchase by means of a single lump-sum payment in lieu of employee contributions as provided in this section in an amount equal to the then present value of the benefits being purchased as determined by the actuary using the member’s attained age, annual compensation at the time of purchase and the actuarial assumptions and tables then in use by this system. The lump-sum payment shall be made immediately upon being notified of the amount due.