The board shall levy the costs contemplated in section 468.201 upon all of the lands of the district on the basis of the classification for benefits as finally established and the assessments so levied shall be paid in one installment unless the board in its discretion shall provide for the payment thereof in not more than twenty equal installments with interest at a rate determined by the board notwithstanding chapter 74A. The board may issue anticipatory warrants bearing interest at a rate determined by the board, notwithstanding chapter 74A. The warrants may be numbered and state a maturity date. The warrants may be sold by the board for cash in an amount not less than the face value thereof, together with accrued interest, if any.