Changing a stem and bars is very easy. But, why do you want to change from threaded to threadless? Nitto makes threaded stems in a variety of lengths (nitto technomic). Do you know what size clamp your bars take, as I do have an extra 6.5 cm terry t-stem, but it only works on 25.4 mm bars, not the more common 26 mm, with a 1" steering tube. It has a pop-tube too to make bar changes easy. profile H20 and salsa also make some nice threaded stems, but with not as much rise as the nitto technomic.