I wish you luck in finding someone with a connection.
If you don't hear from anyone, you might try finding your grandfather's marriage record or a newspaper announcement about it. The first often has his age, place of birth and parents' names, and the second usually has a wealth of names of relatives. One clue often leads to another.
If you get back far enough to find an Alexander Acheson born 1831/37 in Ireland, we might have a connection! I'm pretty sure I've accounted for all the male Achesons in my line since then.