(a) Except as otherwise provided by the Act, any money advanced by the State in the State School Building Fund of a school district which remains an unencumbered balance in excess of the amount required to liquidate all approved costs or expenditures necessary to complete a project shall be returned by the district to the State within sixty days after notice of completion of the construction project has been filed or the project has been accepted by the governing body of the school district, whichever first occurs. The Director of General Services, for good cause, may grant such exceptions to this regulation as he may deem warranted.