Personally I wouldn't even worry about feeding quite yet anyway. Priorities I'd deal with are getting this snake into a very stable environment (temps/humidity), on plain paper towels so you can watch for mites, constant available clean water, two tight dark hides and lots of quiet time with no handling and minimal movement/vibrations in it's enclosure area. At some point you might want to collect a fecal and have a float done. Also watch the closed wound to make sure you don't have an infection under the skin brewing.

I'd let the snake rest quietly for a couple of weeks with close but non-intrusive observing then try a very small first meal, something like a fuzzy rat or very small pup rat and see how it goes. If it starts eating you could then very slowly work it up to a "normal" sized meal if you are seeing good aggressive feeding responses and no regurges over the course of three or four weeks of feeds.

All of this is just the common sense stuff I'd do but please remember only your herp vet can determine this snake's true health status and how to address any needed medical issues. Don't hesitate to see your vet if the snake seems, in your opinion, to need medical intervention or a health assessment.

It's wonderful you are doing this rescue! Remember to protect your collection with good quarantine procedures.