Sure it's good information. Thanks. Not worth the hassle!The answer is surprisingly complicated. The copyright in the musical compositions (aka the songs) is the same as the album, so 95 years from publication in the USA, 70 from release in the EU and most other places.
The actual audio on the other hand...it depends. If the radio station was just doing a live feed the audio doesn't get federal copyright protection if it's of that vintage. If a tape aircheck was being made simultaneously by the station (which they probably were) then it's 95 years from publication. Even if federal law doesn't apply, state "anti-bootlegging" laws may.
Now, didn't you want to know all that?
I just wonder what deal YouTube struck that allows people to upload entire albums concerts whatever with a disclaimer " I do not own the copyright and will remove if requested". Something like that. I know they used to be super strict on that stuff.