UPDATE 6-Venezuela presidential vote looks set for close finish

* Long-serving president faces youthful state governor * Capriles taps into discontent over crime, corruption * From Havana to Tehran, vote has implications abroad CARACAS, Oct 7 (Reuters) - Venezuela's presidential electionlooked headed for a close finish on Sunday with Hugo Chavezfacing an unprecedented challenge to his socialist rule from ayoung rival tapping into discontent over crime and ...