Welcome to the forum.
I suggest you take that gun to a quality tactical class before you put it into use as a self-defense gun, because I think you will discover there are limitations to the choices you have made.
First, you will find that the Mossberg safety and a pistol grip are irreconcilable. You cannot work that safety without completely removing your trigger hand from the grip. That is suboptimal, and one reason that I suggest standard stocks for Mossberg shotguns. Personally I don't like pistol grips on any shotgun, but they work far better on 870s than on 500/590 series because of the safety location.
Second, the shell carrier on the stock will significantly impair your ability to shoot from the left shoulder, and while the chances of you having to do that might seem slim, should you ever need to do it, you will really, really need to do it. It's hard enough to go offside as it is, adding complications is maybe not worth the benefit of additional ammunition on the gun.
Third, you have added considerable weight to the gun with two ammunition carriers on board. It might not seem like much, but the balance of the gun is different and not better set up as you have it. Run that gun with the ammo carriers loaded up through some drills, then run a gun with less stuff on it and see which one points more quickly and accurately; I expect you'll find that the lighter gun works better.
Fourth, a two point sling on a pump shotgun is a great way to carry the gun when you are walking around and a not so good thing to have when it comes time to use the gun. The front attachment point for a two point sling can impair the ability to rack the slide, and with a pistol grip to boot you are inviting tangles. Consider a single point sling; it doesn't work as well for marching around, but it works far better when the time comes for actually shooting. I don't know how or when you plan to use this gun, but I'll make that trade every day.
Unless you sometimes wear armor and sometimes don't, or unless this gun is assigned to users of substantially different dimensions, I'm not sure what good an adjustable stock does for you, but if you like it, rock on.
Now, all that said you have a great shotgun there and I really like the color. If you can make it work like that, drive on, everyone gets to pick what works for them.