David,
Thanks for the concise reply. This means that the1960's text will be OK if hosted in a country with life+70 copyright, such as Australia, since the original author is well dead. Is this correct?
I believe most life+70 countries give 70 years of copyright to anything first published after the author's death, or at least did. According to Wikipedia, the 1960's text would have got 50 years copyright, plus another 20 since it was under copyright when the extensions went through.
At least in the Commonwealth, the copyright regime used to be life+50, or 50 years for posthumous and anonymous works. But it has become fashionable of late to (1) do away with the fixed-term protection for posthumous works; and (2) extend copyright terms another 20 years. Depending on the order in which these operations were applied, and other details that vary from country to country, a posthumous edition published in the 1960s might hit the PD in the 2010s or the 2030s. -- RS