HI Charlie:
I assume there are those watching this BB that may have a line on the supply of old style mortising machines. ( I am assuming for this moment that you wish a human powered device). That said, I also think that an internet friendly shopper should be able to find almost any tool just by asking the right question in the right place. Try one of those auction sites. I will make a couple of calls and have interested parties contact you directly. Good Luck!