First off, I did some very good work with duty shotguns with just a bead,Do-Man. However, when it comes to farther ranges or slugs, a good peep sight is close to optimum, including the Ghost ring job.
BTW, the first Ghost Ring setup I was was one an obsolete Remington pump Rifle around 1956 or 8.It was a standard Lyman peep with the aperture removed. The owner bragged on the speed and accuracy.
One thing, if you add a peep, you'll need a ramp and post or bead to keep it compatible.
BTW, I have a dedicated HD 870 with all the stuff, a dedicated deer 870 with all the stuff,and a bird/clays 870. The latter has just a bead but I can do good work with shot and 00 if needed.I'd consider myself well armed with any of them.