here are the requirements for converting from tourist visa to Non O whilst in country but it is slightly different when you apply from your home country
Why not just apply for 90 day Non O visa in your home country, and then if you feel like you want to stay, open a bank account, put the funds in (800k) and extend for a year, that would be the cheapest route. I started with an ED visa and wished I went the Non O route from the start, much less hassle than TV and ED visa.