Ok roost and window. Do I make the window that it can open in the summer? Roost to bottom of window is 7.5"
I would.
For chickens acclimated to your usual temperatures the occasional weeks in the high 80's to low 90's would be like the weeks of high 90's and 100's for chickens acclimated to my climate. Additional airflow is good then.
Make it so that you can open it different amounts for different conditions to keep the inside the same temperature as the outside.