(a) the adjusted cost base to the taxpayer, immediately before the disposition, of the part so disposed of is deemed to be equal to the greater of i. the adjusted cost base, otherwise determined, to the taxpayer, immediately before the disposition, of the part so disposed of, and
ii. that proportion of $1,000 that the amount determined under subparagraph i is of the adjusted cost base, otherwise determined, to the taxpayer, immediately before the disposition, of the whole property; and