You are in luck, in Sydney from today until the 11th Solar Noon is at 12:01
Then solar noon is actually at noon until from the 12th to the 15th.
You can literally just stand up straight at Solar Noon and your shadow will fall precisely North/South, no adjustments needed.
If you want a more exact shadow you can hand a plumb-bob on a string and the string shadow will be North/South at noon.
Solar Noon for Sydney for the rest of the month:
http://www.timeanddate.com/worldcloc...&afl=-11&day=1