When I first bought my N70, it had a screw-on eye piece. I think they offered screw-on diopter pieces so I replaced mine. Lost it while photographing camp kids in the pool but went back and fortunately found it lying on the concrete. When I bought an N90s, the eyepiece was completely different so no worries about losing it.
Glad you were able to get a magnifying eyepiece. Does it affect the view within the viewfinder? What I mean is do the edges of the photo still show up within the viewfinder since it is a magnifying eyepiece?