As you all know, I'm trying to restore several very damaged fruit trees. One of the apples is probably 30 years old. It literally has been stripped of bark on 3/4ths of the central trunk. There are a few branches holding onto this little strip. I had an idea of taking a scion from it and tapping directly into the root system. My hope was to eventually remove the large, old tree little by little as the scion takes root. It seems this would utilize the mature root system and bring about a healthy tree more quickly than putting the scion onto a new baby rootstock. I just don't see any other way to save it.

Any ideas?