Though it is certainly possible, plausible and likely the the gentleman my have recorded performances at the Surf during that era, there is simply NO WAY this would have gone unreported all these decades.
This would have been big news from the very moment the crash was discovered.
The article indicates there was supposedly more than one person involved in the recording process, making it all but impossible to have remained a secret.
If the gentleman in the story is claiming that the recording existed, but was lost or erased, it becomes an even more compelling myth to talk about.
One BIG clue that the story is more fable than fact?
The mention of the poster. Every serious researcher has concluded that NO SUCH POSTER existed at the time.
All existing posters for the Surf were made later and were based on the other posters for the tour.
At best, it has been suggested that there could have been a small newspaper ad with the tour relevant artwork, but no VERIFIED original poster has ever turned up.