For the purpose of ascertaining gain or loss from the sale or other disposition of property, real, personal, or mixed, acquired before January 1, 1931, the taxpayer may, in lieu of the adjusted basis prescribed by the applicable United States Internal Revenue Code, use the fair market value of such property as of the above date, adjusted for the period subsequent thereto. In all other respects, the gain or loss on the sale or other disposition of property shall be ascertained as prescribed by such Code. (Added 1966, No. 61 (Sp. Sess.), § 1, eff. Jan. 1, 1966.)