The benefits of section 451 of this title shall, and those of sections 451b to 451k of this title may, be extended by the Secretary to (a) any lawful assignee of an unpatented farm unit on a Federal irrigation project who took the assignment in good faith not knowing and not having reason to believe the farm unit to be insufficient to support a family; and (b) any resident owner of private lands on any such project whose lands shall be found to be insufficient to support a family and (i) who, apart from his ownership of the lands to be conveyed pursuant to clause (iii) hereof and apart from his having previously exhausted his homestead right, if such be the case, is eligible to enter unappropriated public lands under section 161 ¹ of this title, (ii) who lawfully acquired his lands as an entire farm unit under the Federal reclamation laws from the United States or, in the case of a widow, widower, heir, or devisee, from a spouse or ancestor, as the case may be, who so acquired them, and (iii) who conveys, free from all encumbrances, to the United States all of his lands served by the project or such portion thereof as the Secretary may designate.