Have a read through the sticky here or even just the summary post linked at the end of the first post of:
Early Stage Kidney Failure in Cat
Some foods to get you started and yes the By Nature Organics Turkey & Chicken has good numbers/ingredients
By Nature Organics Turkey & Turkey Liver, Chicken & Chicken Liver, Turkey & Chicken, Chicken & Mackerel, Beef & Beef Liver
Innova Flex Beef & Barley Stew
Evo 95% Chicken & Turkey
Felidae Platinum
Felidae Cat & Kitten
Felidae Grain Free
Merricks Before Grain 96% Beef
Merricks Before Grain 96% Turkey
Merricks Cowboy Cookout
Merricks Thanksgiving Day Dinner
Halo Spots Stew Wholesome Chicken
Halo Spots Stew Wholesome Turkey
Wellness Turkey, Chicken, Beef & Chicken, Beef & Salmon, Kitten, Wellness Core Chicken Turkey & Chicken Liver (other flavours are too high in phos)
Holistic Select Turkey & Barley
Holistic Select Duck & Chicken
Many more choices listed here
http://www.felinecrf.org/canned_food...od_data_tables
Short light to moderate but not heavy exercise will be good to keep the muscles strong which will play a role in the later stages, given the heart murmur you don't want him to the point of panting/wheezing.
Feel free to post any questions you may have