Hey RC,
Not an accountant but just doing my numbers also.
The gst would be based on the original price of the land. This link might help with the Kim example:
http://ato.gov.au/individuals/content.asp?doc=/content/36907.htm&pc=001/002/026/017/004&mnu=4189&mfp=001&st=&cy=1
also bantax have...