Take a chain saw file and open up the rear notch and replace the front blade with a F/O model. I did that on an 1100 with the same sight set up. Night and day difference.
Also, Midway has the Competition Master Remington 8 shot extension tube for sale. It fits the nut and barrel band already on your gun. I did that for the 870 I use for 3 gun.
I'll be filing the rear sight for sure but I'll likely throw an XS night sight (not the big dot type, regular size) up front (I have one on one of my Express guns and am very happy with it.
That extension will be going on this gun---thanks for that