You do not need High Flow to operate a backhoe attachment. I have a Bradco 609 that I use on my 763C.
When you connect it to your loader, be aware that the hydraulic flow must be in the correct direction through the backhoe attachment. It will not work correctly if the loader is trying to flow it in the wrong direction. You can swap the couplers where you connect to the loader to reverse the flow through the backhoe attachment.
The 609 is actually too heavy for this loader, however it operates just fine. When moving, I crowd the stick and boom all the way in and swing it all the way to one side. It is definitely nose heavy and I try to keep it on fairly level ground when traveling. You can also leave the stabilizers just off the ground when moving on a cross slope.