All money in the acquisition and construction fund not required to meet current acquisition or construction costs of the toll tunnel, and all funds constituting surplus revenues which are not immediately needed for the particular object or purpose to which they are required to be applied or to which they are pledged, shall be invested in bonds and obligations eligible for investment of surplus state money. The authority may provide in the proceedings authorizing the issuance of the bonds that the investment of such money shall be made only in particular bonds and obligations within the classifications eligible for such investment, and such provisions shall be binding upon the authority and all officials having anything to do with the investment.