(taxpayer's residence was destroyed in presidentially declared disaster (involuntarily converted) and taxpayer acquired new residence the following year as replacement residence, but didn't tell IRS that second home was his residence; at time of disaster, basis in destroyed home exceeded its value; taxpayer made improvements to the new home and used some insurance proceeds to make the improvements; taxpayer recognized gain from involuntary conversion due to insurance proceeds exceeding basis in the destroyed home; at time or ruling request, taxpayer had not yet reported gain; IRS said that taxpayer could file original and amended return for year of replacement so as to notify IRS of acquisition of new residence).