Hopefully, I haven't spoken too soon. It seems that this type of tapered square slot in the end is something that is very hard to do. My regular machine shop guy can't do it.
He has suggested I seek another shop who has the equipment to do it. And I just got a call from them that they sold their machine to another company. But I have that companies name and number and may visit with them today....

I'll keep you posted....

The more that say they are interested the more I want to do this....
I'll be taking this adapter with me, to show, tomorrow when I do a tool run to several shops, and Heartwood school....