The principal of, and interest on, such notes may be paid from the revenues of the enterprise. If such notes, or any portion thereof, or the interest thereon, have not been previously paid, they shall be paid from the proceeds of the next sale of bonds in anticipation of which the notes were issued. If any of the principal of such notes is paid from the revenues of the enterprise rather than the proceeds of the sale of bonds, the amount of bonds the local agency is authorized to thereafter issue shall be reduced by the amount so paid from the revenues of the enterprise. The total amount of such notes or renewals thereof issued and outstanding shall not exceed the total amount of the unsold bonds.