I used to work for a wholesale pet food warehouse (UK) and have also kept rescue dogs. So i know quite alot about what foods are available and good for your dog.
We have always started our rescues off on White fish or chicken with a wheat mixer biscuit. You can get these blocks of fish for dogs from your local petstore. Fish is gentle on the dogs tummy, and having been stressed is a good starter food.
If you are looking for a decent dry dog food try Beta Puppy for dogs up to 9 months old which goes on to junior up to 18 months then Beta Pet for general adult dogs until around 7 years of age. They then do Senior for the older dog. Beta Field is for working dogs. James well belloved is ok but i have seen dogs not being able to tollerate it. Bakers is good as it is semi moist. I suggets that any dry kibble is moistened a little anyway as it swells an awful lot even though it is extruded to start with.
Stay away from Pedigree dry and wet foods as they mess around with he ingredience alot. Tinned meat is 75% water and the rest is aditives and a load of C**P.