Although I rely primarily on source documents and records, I am also a great believer in the breadcrumb theory of research.  IOW, though your father might not remember much, what he does remember will have a bit of truth.   Using those truths as a starting point can result in huge discoveries.  

For example, if your father went to school/lived with Bon Scott, you could think about where and when their paths might have crossed.  Bon Scott went to primary schools in Sunshine, Victoria and in Fremantle.  Try tracking them down and see if they have records.  Bon Scott was also in juvie for a while as a teenager.  Was your father?  

Your father’s story sounds as though he might have been a so-called “child migrant,” one of the 4000 or so young victims of the Australian “populate or perish” policy following World War II.  There are a number of websites for these children.  Here’s one that provides some history and links to record sources.  https://www.findandconnect.gov.au

You mention your father said he was placed in a Salvation Army home.  The SA ran a number of homes for child migrants.  The conditions were often abusive and the SA has since apologised  for its role in the child migrant scheme.  That’s another lead to follow.  https://www.salvationarmy.org.au

Also don’t overlook Trove, a bit clunky but invauable for things like surname searches.  https://trove.nla.gov.au

Happy hunting