Bigger is always better with chicken coops and runs, but I think you can actually get the extra space if you're going to make part of the run space covered AND with a door for wintertime so you can 'winterize' that to conserve heat AND give them the needed floor space, and in the summer leave...
Since you're only using the coop for sleeping arrangements, it's **just* large enough with no room to spare, but you won't be able to close the door on them to preserve heat in deep winter. In deep winter, you need an area of 10 square feet per bird, floor space is what is needed here, height...