I'm in the Northern suburbs of Melbourne, I know a lot of people from that area through uni.
Before I go any further, if your son has never attended school before, then there needs to be some way of gradually getting him accustomed to a school environment in which he is surrounded by hormonal teenagers and bossy teachers, possibly starting with just two days a week and gradually increasing, for example. Going in 'cold turkey' would be disastrous, I would think. There will be a lot of things he will need to get used to, and this will take time. For example he will need to get used to wearing a uniform, which in that area usually involves a jacket and tie. He will need to be able to concentrate on his schoolwork amongst the myriad of distractions present in a chaotic classroom. He will need to be able to deal with being ranked academically in comparison to his peers on a regular basis.
As far as the kind of school you should consider, I can't come up with any specific names in that specific area, but as you mentioned anxiety and dyspraxia, I would avoid any really high-end schools with a strong culture of high achievement (which appear to be the norm in that area), at least at first, as this will put too much pressure on him to succeed. Even if he is very smart now, I can almost guarantee you that such a high-pressure environment would be counter-productive. Such schools are concerned only about their school's rankings, and will simply tell him that he isn't trying hard enough rather than actually support him. I am speaking from personal experience at this point. I attended school normally, but by the time I got to VCE I'd had enough of it, it started getting really stressful trying to live up to the school's and the teachers' expectations, and by the time I got to year 12 I had full-blown depression and was on meds for it. I went from being my school's highest-scoring male in year 10 to getting an mediocre ATAR of 77.
So I guess what I'm saying is, you need to find a school that genuinely cares about your son's wellbeing as opposed to their own agenda, and has proper supports in place such as integration aides, understanding teachers who are willing to make some compromises regarding group work, P.E class (which is a social nightmare for aspies due to how useless we are at sports), allowing him to leave the room when he feels socially overwhelmed, etc.
Hopefully at least some of my ramblings have been helpful. 
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Apologies for the excessive length of my posts.