Tread lightly with your cutting tools.

After stripping the body off the pan I cut the floor pans off because they were completely unsalvageable. The passenger side was completely rusted through and the drivers side had been reinforced with fiberglass at some point to fill the holes it was hiding.

Note: I cut the floors off after I did a test fit of my body and recorded the appropriate measurements.

99.99% of the cutting I've done has been with a die grinder and a three inch metal cutting wheel. In retrospect, if I had a reciprocating saw or a nibbler I probably would've saved myself tons of work hours cutting all types of metal. This is one instance where my cheap side beat out my anal side. Normally, I would buy the right tool for the job but I've already got tons wrapped up in tools already (A new compressor and the welder come to mind.) Plus every dime I spend on tools is one less dime I can spend on the car itself. Hind sight being 20/20 I would've sprung for some more "industrial" metal cutting equipment.

Back to the pan. There is a lip along the inner edge of the floor pans where they meet the tunnel. You can see it if you look under the floors near the tunnel. I cut the floors off just outside this lip. After that I took a chisel and broke the spot welds that held the remaining floor metal to the lip. Where the chisel wouldn't work, I drilled out the welds (in the floor metal only not the lip) that were more stubborn. You can see where these welds are if you use a wire wheel to clean the metal up. They look like round little 2mm imperfections or indentations in the steel every inch or so. Try your best not to mess up the lip along the tunnel as this will be where you reattach the new floor pans later. When I finished I cleaned the lips to bare metal with my wire wheel. After the cleaning, I applied WD40 to the bare metal spots to prevent surface rust from reappearing over night. When you live in humid Georgia rust WILL appear overnight if you don't treat the bare metal. When I was done, all that was left was the main tunnel and it looked like an "I" from the top.