I drove it to lunch the other day to get it up to a reasonable speed of 50 MPH and be among traffic. It was around this time I remembered that I don't have side view mirrors installed and lane changes are a bit interesting.
I also noticed that dust from the rotted insulation and rusty bits blows all over the place while driving, making it stinky/dangerous/sucky/hard to see/etc. So this must be fixed ASAP.
I spent about 8 hours this weekend scraping up the loose paint/surface rust from the passenger side of the interior. My main tools were a paint scraper, wire brush, and shop vac. The goal was to remove as much of this junk as possible and vacuum it out of the car to prepare for rust conversion/sealing, and replacing the carpet.
Before:
After:
I threw out a whole shop vac full of loose debris and now much of this area is shiny bare metal.
Then I spent another few hours scrubbing with wire brush while keeping a shop vac running nearby to remove the remaining loose rust dust and surface rust. The floor boards look pretty good at this point, but with a couple small holes poking through, I might weld up replacements before I apply the rust protectant/paint and replace the carpet.