The 607 or 709 backhoe attachments were the standards for the 700 series loaders. These models used the hook mounts rather than the ball mounts.
From what I found online, the 911 weighs 1760 lbs. I have a Bradco 609 Backhoe on my 763C. It weighs just over 1700 lbs. It is definitely on the heavy side for a 763. Once the stabilizers are down, no problems. When transporting I have the boom up and locked and swung all the way to one side. This keeps the weight as close to the loader as possible. Take note that these larger backhoes are also "stronger" and have the ability to shove the loader around.
As long as you are on reasonably level ground, you should be fine, but you will definitely be nose heavy. I bought some tractor suitcase weights that I planned on hanging on the rear of my loader, but never go around to it.
You will also have to find or fab a set of ball mounts. The Bob-Tach is only half of the mount. The ball mounts lock the backhoe to the loader to prevent it from lifting and smashing you into the cab. They also keep the backhoe tipping forward and back while you're digging.
If you can't make the ball mounts yourself, check the availability/price of used sets if you can find them. The factory mount for Bradco was over $1000 for a new one and the one used set I found was $700. So I modified the Case mount that came with it and made the loader side mounts.