Seems to me they made it in 4" for a while. Shortening the barrel is possible but you end up with the writing on the barrel off center. I have seen some blued guns that have been shortened and re-blued. They looked prety good other than the off center writing. A stainless gun poses additional problems, ie re-attaching the front sight and blending it in.
You might be better off finding a 4" take off barrel.