(2) In any such case the board may by such contract provide for spreading the payments over such period as may be agreed upon and may issue therefor serial installment coupon obligations in such number and denominations as it may determine, inclusive of interest at such rate as the board may provide on all unpaid assessments, together with an amount sufficient to pay a proportionate part of the cost of administering the bond assessment program and issuing the bonds authorized under ORS 554.220 and 554.250, including, but not limited to, legal, printing and consultant’s fees, such amount to be determined by the governing body. The installment coupons shall be of such amount and stated maturity as will pay and retire all installment coupon obligations of such designated series evenly, justly and ratably from year to year at the same time, and shall be general obligations of the corporation, payable from a fund as provided in ORS 554.280. [Amended by 1981 c.322 §9]