The handle was cast using my new oil-bonded sand. It came out awesome. It even has the original part numbers on it! I just taped up the splined hole when I made the mold, so it was completely solid with no hole when I cast it.
Making the hex hole was the difficult part. I don't have a rotary broach, so I made a hand tool to do the job.
Here is the finished hex hole. This fits on a hex shaft and there is a screw that goes on the other side of the handle to hold it in place.