The interim binder for a vessel whose stated valuation is established pursuant to this part shall be deemed to have been amended on the first day of the effective period of such valuation, as provided in the notice publishing such valuation, by inserting in the space provided therefor, or in substitution for any value appearing in such space, the stated valuation of the vessel set forth in such notice. A stated valuation shall apply with respect to insurance attaching during the effective period of such valuation; Provided, however, That if there is a substantial change in market values during such period, the Maritime Administration reserves the right to revise the valuations provided for therein at any time during said period; And provided further, That the assured shall have the right within 60 days after the date of publication of a stated valuation or within 60 days after the attachment of the insurance under the interim binder to which such valuation applies, whichever is later, to reject such valuation and proceed as authorized by section 1209(a)(2), Merchant Marine Act, 1936, as amended (46 U.S.C. § 1289(a)(2)).