Ask this in the Ask The Cuemaker area, you'll get prompt, knowledgeable answers.
You can get a radial shaft and sell the other for the cost of shipping really.I would personally just sell the one you have, and buy one with a radial pin. That way you know the new shaft will fit your new pin, and you don't have to worry about any of the possibilities of any minor damage like micro-cracks in the glue holding the pie laminates together from changing the threads on the old shaft. That's one of the beauties of production shafts, they're not unique and can are easy to find new replacements no matter what pin