I just looked at the photos of the car on the rotisserie., if you have that much rust thru in the foot well area I would be willing to bet you have if not thru holes at the least thin metal on the fire wall area by the foot well. I did a few small patches and had to replicate the ribs in parallel on the pass side with new metal. I'll see if I have pics of that too. Hopefully your torque boxes are in good shape.

I also had some areas where the floor was rotted between the brace and rocker on the driver side.