The Secretary of the Interior is authorized, in his discretion, to examine and classify any lands withdrawn or reserved by Executive order of November 26, 1934 (numbered 6910), and amendments thereto, and Executive order of February 5, 1935 (numbered 6964), or within a grazing district, which are more valuable or suitable for the production of agricultural crops than for the production of native grasses and forage plants, or more valuable or suitable for any other use than for the use provided for under this subchapter or proper for acquisition in satisfaction of any outstanding lieu, exchange or script ¹ rights or land grant, and to open such lands to entry, selection, or location for disposal in accordance with such classification under applicable public-land laws, except that homestead entries shall not be allowed for tracts exceeding three hundred and twenty acres in area. Such lands shall not be subject to disposition, settlement, or occupation until after the same have been classified and opened to entry: Provided, That locations and entries under the mining laws including the Act of February 25, 1920, as amended [30 U.S.C. 181 et seq.], may be made upon such withdrawn and reserved areas without regard to classification and without restrictions or limitation by any provision of this subchapter. Where such lands are located within grazing districts reasonable notice shall be given by the Secretary of the Interior to any grazing permittee of such lands. The applicant, after his entry, selection, or location is allowed, shall be entitled to the possession and use of such lands: Provided, That upon the application of any applicant qualified to make entry, selection, or location, under the public-land laws, filed in the land office of the proper district, the Secretary of the Interior shall cause any tract to be classified, and such application, if allowed by the Secretary of the Interior, shall entitle the applicant to a preference right to enter, select, or locate such lands if opened to entry as herein provided.