(in 1972, petitioner transferred stock in family corporation to other family members pursuant to settlement of family dispute; no gift tax return filed, and IRS now asserting $1.1 million in unpaid gift tax on basis that transfer constituted gift; petitioner claims that transfers were nontaxable settlement payments; interest on purported gifts anticipated to exceed $1 million; because no gift tax return filed in 1972, statute of limitations for asserting tax never commenced and all tax years remain open).