If I'm reading you right, you have a Remington with BARREL mounted front and rear rifle sights, and you want to replace the rear blade with a peep.
First, I don't know of anyone who makes a peep that will fit the Remington factory sight.
Second, peep or ghost ring sights only work when the aperture is close to your eye.
Mounting a peep that far forward don't work too well, but to be fair, some people use them on SKS and AK rifles.
The problem here is, unless you can get the factory blade modified, there's no practical way to get a peep that will fit the factory sight.
Remington brazes their sights on with high-temp brazing in electric furnaces.
In order to get the factory base off, you have to either heat the barrel to a red heat until the brazing melts, or you have to cut the sight off.
What you can do rather easily, is to reshape the stock factory sight blade and braze or even soft solder on a new blade with an aperture hole in it.
This is rather easy, with all that's required is to file the rear of the rear sight blade flat, then make up a flat blade with a hole in it, that you can solder or braze on the sight.
To install a receiver mounted ghost ring sight requires drilling and tapping the receiver, AND you still have to get the barrel mounted sight base off the barrel, unless the base minus the sight sliders is low enough that it doesn't interfere with the new ghost rings vision of the front sight.