The proceeds of the bonds shall be used solely for the payment of the cost of the project or combined projects and shall be disbursed upon requisition or order of the chairman of the authority under such restrictions, if any, as the resolution authorizing the issuing of the bonds or the trust indenture mentioned in this chapter may provide. If the proceeds of the bonds, by error of calculation or otherwise, are less than the cost of the project or combined projects, unless otherwise provided in the resolution authorizing the issuance of the bonds or in the trust indenture, additional bonds may in like manner be issued to provide the amount of the deficit, which additional bonds, unless otherwise provided in the resolution authorizing the issuance of the bonds or in the trust indenture, shall be deemed to be of the same issue and shall be entitled to payment from the same fund without preference or priority of the bonds first issued for the same purpose. If the proceeds of the bonds of any issue exceed the amount required for the purpose for which the bonds are issued, the surplus shall be paid into the fund provided for in this chapter for the payment of principal and interest of the bonds.