How bad is this? ( Clutch Drum )

Just took apart my 727 for an inspection/overhaul.
Its my first time and while inspecting the interior parts i found this on the inner bore of the front clutch drum:




Im currently reading the TF727 Transmission book as im doing this and it said in the inspection note that damage here is not good at all.
This scratch stops my fingernail easy while drawing it over the scratch.

Is this something to fix or can i let it be ? Just want to be on the safe side and take my time with this reabuild :)

Thanks everyone!

Chris