Hi Tom...remember, just like anything else....if you
want a good mechanic listen to those that have had success
and gone to that mechanic...rather than they 'heard' or saw an advertisement about the guy.
Listen to a financial advisor that is very wealthy due to his investments.
Don't listen to advice from a poor person.
You get my meaning.
Make sure the person has experienced Samadhi or Nirvana, as you asked.
My unsolicited suggestion.
Similar to the stories of Vivekananda trying to find a guru/teacher...
the question he asked was simple,
"Have you seen God and can you show me God."
It was Ramakrishna that finally said, "Yes", btw.