Sheldon,
I've had gum grafts post-radiation, but not so soon after (as I recall, I had at least a few years between radiation and the first graft). It was done by the same oral surgeon who diagnosed my cancer and who assisted in my glossectomy and neck dissection, and I know he took a lot of precautions in doing the graft because of my history. I had no problems with it, and it was relatively successful.
As it happens, I just had a visit with the periodontist today, because the area around my upper wisdom tooth (on the side that had most of the radiation) has been showing significant degradation of the bone. Right now they're using antibiotic therapy in that region in the hope that it won't become necessary to pull the tooth.
Cathy