Hi Megan, welcome. Your future posts won't need approval so post away.

I'm so sorry about your cat! What a terrible situation to find yourselves in. How did the break happen? 

It's tough to make a decision like this when it comes to an older, outdoor cat. But if he is otherwise healthy there is no reason why he wouldn't do well. Yes front leggers have a bit more of a challenge but cats are so agile that we rarely see that as an issue in them, moreso in dogs who are heavier and less agile.

There's no need to change anything about his activity level if he's not overweight, so you wouldn't need to do much to modify his routine. However, being an outdoor three-legged cat poses a lot of risk. One less paw to defend himself is not good, also jumping from high places isn't either. One way to resolve that is by building a catio, which lets him enjoy the outdoors yet be completely safe. Some cats can thrive outside, like Fang did for many years. But again, it's risky.

What does your vet think about him being a good candidate?