The finish is probably Armaloy which is a type of hard chrome finish that was popular during the 70s and 80s. I don't recall if they did in house gunsmithing. Your 28 received a model 24 barrel with patridge front sight. The cylinder could have been bored to .44 Spl specifications or a .44 cal cylinder could have been fitted to your 28 frame. Model 28 conversions were not uncommon during that era as .44s were difficult to come by. Most were great shooters as I imagine that yours is.