I know of somebody who did this and survived. Symptoms did not include separation of blades, gearboxes or drivetrain but he only went to 120% +- a few %.
I suggest taking a look at the maintenance manual for procedures to be followed in the event of a rotor system over speed. The components to be checked should give you guidance as to the likely failure points.
Please be seated when you open it up......
Edited to add, this was a governor runaway, not something that was "allowed" to happen.