Notwithstanding the provisions of section
282 of this title on the revocation not later than 10 years after the date of approval of this Act, of any order of withdrawal, in whole or in part, the order or notice taking such action shall provide for a period of not less than six months before the date on which it otherwise becomes effective in which the State in which the lands are situated shall have a preferred right of application for selection under this section, subject to the requirements of existing law, except as against the prior existing valid settlement rights and preference rights conferred by existing law other than section
282 of this title, or as against equitable claims subject to allowance and confirmation, and except where a revocation of an order of withdrawal is made in order to assist in a Federal land program.