[partially lost] The God King (1974)

I have been searching for a copy of The God King - a 1974 Sri Lankan historical fiction film set in Sigirya. The film was directed by Lester James Peries.

The film is based on the historical clash between brothers Kasyapa and Moggalana on Sigiriya Rock.

I have been unable to find a copy; digital, dvd or video despite looking for months now. I would like to find a copy for my aging father in law, who saw the film a long time ago. I see that it has previously been on some streaming platforms but not anymore.