With that space, your adult birds are going to need to free range several hours a day, every day, consistently. It's really a small space for that many birds. You don't list your location, but as mentioned by lazygardener you'll need to evaluate your climate. How often are the birds going to be confined due to bad weather? Even self-confined?
My other thought is what about vacations or illness, things like that? If you're suddenly unavailable to do the day to day care for your birds, is someone else going to be able to come supervise, or even let them in and out? IMO it's much better to have a larger coop, for contingencies like that.
