Keto and IF are just preferences. Personally, I am not a fan of keto, but if you like it and can function, keep it. Same thing with IF, if it fits your lifestyle, keep it.
In terms of calories, I would eat right at your TDEE and I would also keep protein high, 1.25-1.5 grams. It is not so much to retain your muscle, but more or less to help you recovery. If you have an injury, or are recovery from a surgery, your body is using energy to help your body heal. Take it from someone that had a heart transplant and recovered extremely fast. Keep your cals up and protein up. Your body needs it.