IRA owner dies in 2001 at age 76. Spouse is sole beneficiary and elects to treat IRA as her own. She is age 71. For the 2002 minimum distribution, is the calculation based on her single life expectancy or may she base the calculation on the Uniform Lifetime table since she has now designated beneficiaries on the account?

Even if she didn't have beneficiaries she would use the uniform distribution table. Account holders never use the single life table.