I remember a thread on one of these builder forums complaining that modern threadless steerers are overbuilt and their wall thicknesses haven't changed from the threaded steerer days. So I measured the thin section of a Columbus 1 inch from the 80s and compared it to a Nova 1 1/8 that I just put together. They were both 1.5 mm thick. If you have a way to find the thickness before you buy, you might be able to get it threaded yourself. Also, on Nova's site, the butt profiles of the threaded and non threaded are the same.