Nice repurposing of the building and well thought out run area.
You will likely find that the birds will be roosting on the upper shelf and whatever roost branches you have higher up. You might need a bit higher barrier on the nest areas to keep the shavings/hay/whatever in. Also, I was thinking about your drain holes in the floor. I think you'll need to cover them with a board of some sort between wash downs or they will get plugged with whatever you are using for flooring material.
Thanks. I will watch the drain hole thing. I did make the holes large enough that a snake could get through would make chicken food--but not the other way around. I used a bit large enough I can use a handy stick to knock em clear. Stay tuned.