169.435.  Revocation of election of coverage made on or ninety days after October 13, 1961, procedure, effect on creditable service. — Any member, who elected on October 13, 1961, or within ninety days thereafter to continue contributions and receive benefits as provided by the law theretofore, may revoke such election by written application to the board of trustees and, upon making the payment of such amount, including interest, as is required to make his total accumulated contributions equal to what they would have been had he not made such prior election but instead had made contributions to the retirement system established by sections 169.410 to 169.540, shall receive credit in such system for equivalent service.