Reduced Diameter Head Studs

Does anyone know of a reduced diameter head stud for the SBM? I have seen them for motorcycles and a few other auto engines, but can't find anything for the Mopar. It would have to be 1/2-13 on one end, reducing to 7/16 or less on the smooth shank and top threaded portion. Looking for a way to gain a little more room in the port on the common wall side.