Any member who was an elected police magistrate or justice of the peace serving as a magistrate of the Circuit Court for the duration of his elected term, who has not elected coverage in a retirement system financed in whole or in part by public funds for such elective service, may receive credit for such service, beginning as of January 1, 1963 and for the remainder of his elective term of office by making contributions for the period of such service based upon the member’s compensation and the contribution rate in effect at the time the service was rendered with regular interest thereon from January 1, 1963 until the date of payment. These contributions must be paid in full before retirement either in a lump sum or in installment payments in accordance with such rules as may be adopted by the Board.