I don't know enough about the history of this problem to say exactly how it is to be done. But left of the crack is a good right hand edge and a left hand undercling. If you can pull on from these, throw to the good downsloping 10 finger edge at about 8 feet. Then without using the crack, muckle or mantle over. If starting this way is breaking your heart, use the right hold and give the ol' heave ho from the ground to gain the 8 foot edge with your left hand and go from there, it will probably offer you a more equal challenge for the grade.