I remember seeing 'Korovo' being offered for sale at Gretchen Wheen's nursery in Sydney about 20 years ago, so there may still be the odd specimen or two surviving in Sydney. I regret not purchasing it at the time.
It would be great if there are more out there. Clearly this one has been alive for over 80 years, so it must be tough and healthy. The reviews in the references are glowing.
Hopefully the owners from Orange might be able to propagate it from cuttings. If their bush has that provenance of being 'Korovo' and also matches the photos and descriptions etc., I see no reason to doubt it as being 'Korovo'. It would be a good one to spread around again.