I have a standard Mk II that I bought new several years ago....I didn't like the fixed sights either, so I went and bought a set of Millet adjustable target sights with an orange front and a white outlined rear. I've taken some small game with mine (mostly rabbits) and I put an nice set of wood grips on mine when the plastic ones broke.
FWIW, I found it difficult to find a holster that would fit it with the new sights.....then I found a copy of a Walther P-38 flap military holster, and problem solved.
