upon the occurrence of a substantial default in respect to the requirements and conditions to which the public housing agency is subject (as such substantial default shall be defined in such agreement), the public housing agency shall be obligated at the option of the Secretary of Housing and Urban Development, either to convey title in any case where, in the determination of the Secretary of Housing and Urban Development, (which determination shall be final and conclusive), such conveyance of title is necessary to achieve the purposes of this subchapter and the United States Housing Act of 1937 [
42 U.S.C. 1437 et seq.], or to deliver possession to the Secretary of Housing and Urban Development of the project, as then constituted, to which such agreement relates:
Provided, That in the event of such conveyance of title or delivery of possession, the Secretary of Housing and Urban Development may improve and administer such project as low-rent housing, and otherwise deal with such housing or parts thereof, subject, however, to the limitations contained in the applicable provisions of the United States Housing Act of 1937. The Secretary of Housing and Urban Development shall be obligated to reconvey or to redeliver possession of the project, as constituted at the time of reconveyance or redelivery, to such public housing agency or to its successor (if such public housing agency or a successor exists) upon such terms as shall be prescribed in such agreement and as soon as practicable after the Secretary of Housing and Urban Development shall be satisfied that all defaults with respect to the project have been cured, and that the project will, in order to fulfill the purposes of this subchapter and the United States Housing Act of 1937, thereafter be operated in accordance with the terms of such agreement. Any prior conveyances and reconveyances, deliveries and redeliveries of possession shall not exhaust the right to require a conveyance or delivery of possession of the project to the Secretary of Housing and Urban Development pursuant to this paragraph upon the subsequent occurrence of a substantial default.