I am working to install a 600kW or so wind turbine on land in CA, but am having trouble finding a new turbine to purchase. It seems that all the manufactures have moved to larger turbines. My land is limited to a max height of 200 feet which mean that I am limited to around 45 meter rotor diameter with 40 meter tower. I need help finding a wind developer and/or turbine manufacturer that still works with medium sized turbines. Thank you.

Have you looked into the Vestas V52-850? Its 850kw, a little bigger than 600 but they are still being produced and can be mounted on a 44m tower.