Sorry about all of that trouble. First, I have good news regarding the DNA on the Adrsheal line, it has been done. Mine is a very close match too. We suspect our common ancestor is John 4th of Ardsheal. More on that another time.
I am finding that the DNA math is best for narrowing focus on research. It will eliminate many possibilities and dial into a specific century and region. I would strongly recommend this avenue to get started again. FamilytreeDNA.com
Any chance you have a scan of an early image of Duncan, his sons or grandsons? Also, you wouldn't still have that tree you mentioned do you?