I would replace that drum and the band that goes around it. Also the sprag clutch that is between the drum and the center support might need replacing as well as the center support.
Check the planetary gears in the back of the drum as well for any damage.
All the scoring was done when that assembly moved forward and back and may have hidden damage in the other pieces behind it.
Hotrod Lincoln can speak much better than I can on what it might need, but look everything over close for damage.
