If you can get her healthy it will. I have one we found in the yard that was starved and within hours of death. She is now 9 years old and beautiful. Being that yours is a runt, are you feeding her kitten chow, I would keep her on that for the added vitamins and maybe supplement with Nutri-cal.
Since you are having a lot of health issues I would recommend getting the book The Encyclopedia of Natural Pet Care by C J Puotinen. I don't use everything in the book, since I have taken in 17 cats it isn't possible for me to do, but I supplement their diet with the raw food diet on a regular basis. Since I started doing this my vet bills have become almost non-existent. The book has a lot of good suggestions, and the more of it you use the better the health of your animals. I've found this to be true.