The peep sight, if your eyes are not too bad, really helps, as the aperture close to your eye, improves your vision, making seeing the front sight easier.
It's also faster than the standard sight, and the longer sighting plane of the receiver mounted sight makes accuracy better.
This is not true of so called aperture sights that mount in the original sight location on the barrel. They are too far ahead to have the desired improvement to your vision, and have the original short sighting plane. IMO they are little better than the old buckhorn sight arrangement.
For a top eject, (I hate scopes on levers they destroy the aesthetics, and ruin the fast handling characteristics IMO) there are two options. One, as you already pointed out, is the side mount.
The other, is the scout mount scope. This places a long eye relief scope out on the barrel ahead of the receiver. I've never used one, however I've held one. The long eye relief makes for fast target acquisition.
Another option is the Bushnell Holosight type rear sight, or the aimpoint type.
Both require batteries of course, and have issues in bright sunlight, however, they are about as fast as you can get.