Giants,
I donated at age 67, and am a physician. I read about all there was to read in medical journals, medical & surgical & transplantation textbooks, etc. Not much research has been done; that is, your (and my) question has not been studied adequately. The inadequate research indicates that,
on average, the recovery percentage is a bit less -- about (as I recall) in the 60%-70% recovery range, compared with 65%-75% recovery range of younger donors. Notice the overlap, however. After you get your tests, especially the more accurate test to measure GFR, discuss your results and your question about age with the transplant center's nephrologist &/or consult an outside nephrologist. Also, please read the topic "The latest on GFR" at the top of the first page of the Forum.
Also, please feel to e-mail me, to set up a time to discuss by phone.
All the Best!