For detailed information on older Malvern Star bikes the best place to start is at:
http://www.ctuc.asn.au/
the site currently contains a large amount of information on the company and the people behind Malvern Star and some information on the bikes that they produced. Later in the year I hope to add to the site a great deal more information about the bikes, particularly the lightweight racing models. In the mean time, if you contact me off list I should be able to provide some information about this particular frame. From the serial number I would say that it was a custom built frame, probably built in Adelaide rather than at their main factory in Melbourne.
Rolf Lunsmann