Dig away.
Heller offered this speech to EVERY Labour leader from Kinnock onwards, and is delighted that Corbyn used extracts from it. He offered it to Corbyn, and its use was NOT unauthorised.
Don't believe me? Well, read what Heller says himself.
http://www.theguardian.com/commentisfree/2015/sep/29/jeremy-corbyn-labour-leader-conference-speech
Where did I say it was unauthorised?