The acquisition, construction, reconstruction, improvement, betterment or extension of any undertaking and the issuance in anticipation of the collection of the revenues of such undertaking of bonds to provide funds to pay the cost thereof may be authorized under this law by ordinance or resolution of the governing body which may be adopted at a regular or special meeting by a vote of a majority of the members elected to the governing body. Unless otherwise provided therein, such ordinance or resolution shall take effect immediately and need not be laid over or published or posted. The governing body, in determining such cost, may include all costs and estimated costs of the issuance of said bonds, all engineering, inspection, fiscal and legal expenses, and interest which it is estimated will accrue during the construction period and for six months thereafter on money borrowed or which it is estimated will be borrowed pursuant to this law. The approval of the voters of such municipality shall be required and on such approval such bonds may be so issued and sold, notwithstanding any provisions of any law of the state of Missouri or the charter, bylaws or other regulations of any municipality, or any limitations upon the incurring of bonded indebtedness prescribed by law of the state of Missouri or the charter, bylaws or other regulations of such municipality. A four-sevenths majority of the voters voting for the proposition shall constitute an approval as herein provided; except that, if the bonds are to be issued for any of the purposes set out in Article VI, § 27 of the Constitution of Missouri, a simple majority shall constitute approval.