from my girlfriend who spent time there: There aren't any shuls per se in Cuzco, but there are tons of Israelis and a few of the Israeli restaurants have Shabbatesque gatherings. This usually means Kiddush and dinner. If you're looking for a real service, you might be out of luck in Cuzco. I would go to one of the Israeli restaurants (either Chalom Cachol or Nargilah at the top of Gringo Alley) and ask around.