The general law relating to taxation and the collection of delinquent taxes, as now existing, shall apply to cities not within any county insofar as not inconsistent with the provisions of sections 141.820 to 141.970, except that cities not within any county may hereafter elect to operate under the provisions of chapter 140, the general law relating to the collection of delinquent taxes, by the enactment of an ordinance by the legislative body of such city.