Hello emcee:
welcome to the forum.
It's been a few years since I've had to deal with kidney failure, but here are a few web sites that I found very handy for information. You might already have it if you have been doing any research, but in case you don't, here it is.
http://www.felinecrf.org/symptoms_treatments_index.htm
here's one from Dr. Lisa Pierson's - a little information on protein that could be of value. I know when I was dealing with the issue that I was working with, the vet I had at the time had issues with the prescription diets and the lack of protein.
There seems to be a lot of controversy over protein. As Soos suggests, get hold of an integrative vet who is knowledgeable in feline nutrition and especially for CRF. Make sure you feel comfortable working with the person. That means a lot.
http://www.catinfo.org/#Kidney_Failure
hopefully if you haven't come across this info, it will be of value.