Where, in any county prior to March 13, 1961, a majority of the legal voters voting on the proposition to issue county bonds and voting to levy an additional annual tax for the payment thereof in excess of the statutory limit of 12 1/2? per $100 valuation of taxable property and in excess of all taxes levied by said county for general county purposes without a referendum and in addition to and in excess of all other taxes authorized or permitted to be levied by said county within the constitutional limit of 75? per $100 valuation of taxable property in said county, have voted for bonds and additional tax in excess of statutory limit of 12 1/2? per $100 valuation at a referendum and held for such purpose, and notice of such election contained a statement of the proposition to be voted upon, and the proposition was substantially in the form as set out by statute, such referendum is hereby validated in all respects, notwithstanding that the proposition stated the statutory limit of 12 1/2? per $100 valuation instead of such statutory limit as reduced by the applicable provisions of the General Revenue Law of Illinois.