The board of governors shall accept the proposal of the board of education for the payment by the board of education to the board of governors in fulfillment of any obligations of the board of education with reference to retirement benefits for the persons included in the provisions of section 2 and 3 of the sum of $1,000,000.00 on or before June 30, 1965, in approximately equal annual installments with interest of 3% per annum on unpaid balances after July 1, 1958.