I found this picture of a concert poster, but not for any fact concert of Queen.
It may be a concert that was planned in 1974 in Los Angeles?
Sorry for my bad english.
Just as an reminder. There is a 74'Tour date in question,
7 December in Siegen or Singen / Germany. I 've tried to get information via different sources. But unfortunately there isn't much of an result so far.
To my personal belive it's a "phantom gig" that never happend, but you'll never know.