As I'm not from Aus, I don't know the layout down there. As I see it, your biggest problem will probably be shifting the perception people have of OTTBs. Alot will avoid them like the plague - as soon as they hear OTTB they run a mile. Not saying all people, but it is quite a common reaction.
As a business venture, I don't know how well it would work. I just can't see making much money when you look at how much you'll have going out in expenses. If you want to make much profit your going to need to compete and show successfully, so that people don't just assume they are an ordinary OTTB.
As an attempt to find the horses new careers and homes, I say go for it.
Whatever you decide, best of luck :)
Stop for a minute, open your mind, learn. You may not agree with what I say, I may not agree with what you say but we will both learn something new.