Not read your link yet Joe, so might confirm this, but I believe the 50 year law is dated from first official release, not the recording date.
For example, Billy & The Moonlighters 'Little Indian Girl' was first officially released in something like 1977, even though its(presumably) an early 60s recording...so it's protected by the 50 year law until 2027.
So any unreleased 60s tracks that are legally released now would be covered until 2062......can anyone confirm if this is correct?