Hi,
it gets very expensive in time and costs if you try chased down and buy all the bits to complete your Motor so that is not the way to go I would suggest. If you know that your block is okay you could look for someone that wants to get rid of an engine where the block is damaged but everything else is okay or get a complete engine that is suitable for rebuild and offer your block for sale to someone else that needs a block.
I don't know of any local engine builders to Orange but there area couple of reputable builders around Sydney, or Melbourne, that could build you something to suit your needs. If you are looking at ready to go engines on eBay or Gumtree etc. do your homework first on whether they are really what you expect or are they mutton dressed up as lamb.
Terry