From a Google search it appears the '96 Attitude has a threadless fork, headset and stem and, I assume 1-1/8" diameter steerer. By a "more conventional set up" do you mean you want to change it to a threaded fork and quill stem? If so, there is no simple adapter that will accomplish it. You will need a new fork, a new headset and a new stem. None of this will be cheap.