If you have the money and space I would absolutely recommend an actual aviary. They carry both indoors and outdoors. Check with Aviary Connections. It allows so much more room inside for the bird once the toys, perches, etc; are added. Esecially a Greenwing which is a large bird to begin with.
If you don't have room for that the largest Macaw cage you can find. Which you'll probably spend the same $$$ wise. Then again space may be of an issue.