My belief is that this song was done in standard tuning. His C tuning did not come in to use until the 1970s. However, even his early playing had a bit of mystery to it because he knew his way so well around the instrument. The CD "Both Ears and Tail" has a rag performed on it and the guitar work is very accomplished. That was in standard tuning and I think comes from the year 1966. Martin was destined to become one of the great guitarist., Listen to his skill on the recent Ruskin Mills CD. Long may he be fruitful!