Do you plan on running an optic or irons?
I have heard / read you can’t just throw any AR rear sight on there and be good to go. I believe you will need a specific T91 rear sight or you have to replace the front sight post (not the entire front sight, just the post). But last time I looked into this, both the rear sight and front sight post were out of stock.
Good luck, let us know if you get one and what you think.
Atlantic firearms has them.