Very few of the 1895's came with the upper tang drilled for a tang sight. But, a few did so you might be able to use an 1894 style tang mounted peep. The other "factory correct" peep would be to find an original Lyman 21 or 38 and have it mounted which, of course, means drilling and tapping the receiver. There is a 3rd much less common bolt mounted peep but I can only recall seeing that in pictures so I'm not sure exactly how it mounts.
