It depends on a lot of things, bantam or full sized chickens, how much they are locked in the coop versus being able to get in the run either due to climate or other reasons, your management practices, feed and or water in the coop or run, some breeds take confinement better than others, personality of the individual chickens, to name just a few. You will probably be OK if they can get in the run a lot of the time. You may need to manage the poop load a bit more than many of us have to but you'll know that if it starts to smell. The main thing to watch out for is pecking and cannibalism. If they are stuck in too small a space too long, they may get bored and start picking on each other. This can lead to cannibalism. With that large run, I think you will be OK but you might want to watch them closely. And don't get any more without making some changes.
Good luck!!!