Matt and I got out in the shop this morning and did a little work. In addition to the full floor pan being replaced, we also needed the toeboards replaced. This is the angled piece that joins the firewall to the floor pan.
I didn't take a pic of the passenger side before we started, but here is a pic of the drivers side. As you can see, it's pretty well rotted away. We were very fortunate that the frame rail extensions that the toeboards weld to are in good shape.
We started with a toeboard repair panel from NPD. This is 18 gauge sheetmetal that is stamped in a shape that closely resembled the original shape, but it was far from "drop in and weld" piece.
We were having a very difficult time getting the complete unit to fit properly, so Matt cut the repair piece in half. This worked out much better. Here is the right side welded in.