The lien described in section 622 of this title upon land covered by unpatented entries may be enforced upon said unpatented lands by the sale thereof in the same manner and under the same proceeding whereby said assessments are enforced against lands held under private ownership: Provided, That in the case of entered unpatented lands the title or interest which such irrigation district may convey by tax sale, tax deed, or as a result of any tax proceeding shall be subject to the following conditions and limitations: If such unpatented land be withdrawn under the Act of June 17, 1902 (32 Stat. 388), known as the reclamation Act, or subject to the provisions of said Act, then the interest which the district may convey by such tax proceedings or tax deed shall be subject to a prior lien reserved to the United States for all the unpaid charges authorized by the said Act, but the holder of such tax deed or tax title resulting from such district tax shall be entitled to all the rights and privileges in the land included in such tax title or tax deed of an assignee under the provisions of section 441 of this title, and upon submission to the United States land office of the district in which the land is located of satisfactory proof of such tax title, the name of the holder thereof shall be indorsed upon the records of such land office as entitled to the rights of one holding a complete and valid assignment under section 441 of this title and such person may at any time thereafter receive patent upon submitting satisfactory proof of the reclamation and irrigation required by Act June 17, 1902, and Acts amendatory thereto, and making the payments required by said Acts.