Gotta love interior work. I had similar rot. I had to redo the entire driver floor, kick panel, cab mount, inner and outer rocker, inner and outer cab corner; on just the driver side. Passenger side only need some patching and a cab corner.
I didn't take many pics since I was just trying to get through it. However, in my case I wanted to know why I had that much rot on one side. Sure, old truck and common rust spots, still wanted to find out and prevent it from happening again. I started pouring water over it. Door seals were OK, replaced them anyway. Windows were the same.
Turns out it was two things; the drip rails above the door (mounting holes). However the majority of it was coming from the firewall/cowl. The factory seam silicone stuff had deteriorated towards the driver side letting water go down in the engine bay on the firewall. A rust hole formed where some lines came through the wall, rain water traveled that path into the cab just below the pedals. Had a vinyl floor that didn't let it evaporate. Problem found.
I peeled all old seam stuff out and applied fresh stuff. No more leak. Too bad I found out after I did engine swap cause the hole is too tight of an area to cut and weld. That's a later project.
With the seat, I restored mine and while I was in there I put some heated seat/back pads in. Highly recommended if you're in a cold state.
