Notwithstanding section
720
(b) of this title, the Association shall issue obligations under section
720
(a) of this title in an amount sufficient to finance such agreements and shall require the Corporation to assume any such obligations. The aggregate amount of obligations issued under this section and outstanding at any one time shall not exceed $300,000,000. The Association, with the approval of the Secretary, shall designate in the final system plan that portion of such obligations issued or to be issued which shall be refinanced and the terms thereof, and that portion from which the Corporation shall be released of its obligations.