Where rights of priority have been granted pursuant to the provisions of this chapter to Government-owned property, it shall be offered for sale to priority purchaser by giving notice to those eligible for such priority. Such notice shall (1) be in such manner as the Commission shall prescribe, (2) identify the property to be sold, and (3) state the terms and conditions of sale and the date of the offer which, in the case of occupants of single family or duplex houses, shall expire not less than ninety days after the date of the offer.