I was able to adapt Bert’s Graves index so it works with the MDR. (A big thank you to Bert!) A local machinist made and seated a steel bushing and added a set screw. It is a little bigger in diameter than the MDR index, but works well. This seems to be a good solution for this machine. I haven’t cut a stone yet, so the final determination with be after that is done. So far, it looks very promising.