I can speak from experience as I tried to take a damp cloth to a red "file photo" stamp on the front of this photo...
baberuthbatting.jpg
Although I did remove a good deal of ink the photo started to wrinkle. After telling two friends who are experts in the field, they convinced me to only view my photos and leave all other things to a professional.
The trouble is, there aren't that many photo conservators around, and I live in L.A. for God's sake.
My advice would be to contact fellow board member Dr David Cycleback and he should be able to steer you in the right direction.
Sincerely, Jimmy