The proper officials of each township of the second class, if they have not previously done so, shall, at the time of fixing the tax levy for the years one thousand nine hundred thirty-six and one thousand nine hundred thirty-seven, reduce the said tax levy for road and street purposes by an amount, approximately equivalent to the amount to be expended in such township under the provisions of this act, as compared with the amount levied for road and street purposes for the year one thousand nine hundred thirty-three, except that proper provision shall be made by the townships for interest, sinking fund, debt repayment charges, and such other administrative and overhead expenses as may be necessary.