I'm sorry, but as a general rule of thumb you can figure that any coop which is measured in inches is too small to keep chickens in.
The usual guidelines (do read @Ridgerunner's excellent article, which explains why they are *guidelines* rather than rules), are that each adult, standard-sized...
Here are some helpful articles on integration:
https://www.backyardchickens.com/articles/integrating-new-birds-at-4-weeks-old.72603/
https://www.backyardchickens.com/articles/my-coop-brooder-and-integration.74591/...