The higher voltage is fine, but Radio Shack caps will likely fail in a year since they're general purpose caps not made for switching power supply circuits. You should instead use caps with low ESR, such as Panasonic FM, Chemicon KZE, Sanyo WG, Rubycon MBZ or MCZ, or Nichicon HM, HN, or HZ. Mouser, Digikey, and BDent carry them, but most Ebay dealers sell counterfeit versions.