Spare tire well replacement question

The bottom of the spare tire well in my 70 duster is rusted out pretty bad. I’m looking into buying the replacement panel from Sherman but I’m wondering how far up the spare tire well the new panel will go.

has anyone replaced their spare tire well with a new panel? And, how far up does the new panel go? A couple inches or all the way up to the flat point of the trunk?

hope that makes senses lol. Thanks