Stem shifters I'm not sure about but DT shifters it's possible. Shimano make them in 8 and 10 speed. I am using SL-R400 8 speed shifters mounted on Campagnolo Friction shifter bosses from the early 80s (perfect fit). Shimano also have DA 7900 10 speed DT shifters. I am very happy with mine, the shifts are very precise and fast. You do still have to take your hands off the bars but you can drop three or four gears at a time and it retains the look of a classic bike.