Welcome to BYC. This is a good idea. Many people have made this conversion and their flocks have been happier for it.
Where, in general, are you located? Climate matters, especially when designing housing.
You should write this up as an article on modifying a pre-fab to work better. Love your little metal awning! Is it roof flashing or something else?
Since you're in a hot climate you should monitor the temperatures inside the coop. If it still gets hotter inside than out I suggest that you take...