The trick to fitting a backhoe is the secondary anchor to the frame. Fitting to the Bobtach should not be much of an issue. If you are at all handy, or have a handy friend, you should be able to fabricate a secondary mount. Do a search on the forum - you should find post and pictures of what others have done.
I would start by seeing what is available for a price you want to pay in your area, then deciding on how hard it would be to fit it to your machine. The older 709's utilized a trailer ball mounting system, which I have seen adapted to a lot of different skidsteers over the years.
Bradco is another brand to look at - they should be able to tell you what it would take to mount one of their units on your machine.
Depending on what you plan to do with the hoe, you may also want to look at a Bobtach hoe - they are easy to fit, readily available, and cost effective. I love mine.