You should only need to remove the 6 bolts that secure the pulley and dampener to the hub. If you discover that the front crank seal needs to be replaced then "Yes", you will need to remove the 27mm bolt. Most over the counter torque wrenches will not go to the 400-NM mark so you may need to locate a torque multiplier. A rental yard that carries a good selection of hand tools may have one available so you might want to call around. If the rental yards are unable to help check with a local big rig repair center and see if some one would be willing to help a brother out. These professionals need to handle large nuts (the trucks ) and bolts so I am almost certain somebody may be willing to help if you need it.

I'll be available over the weekend if you need any other tips.