I've been planning on buying the Classic Industries floorpans, but what do I need to do to fix part of the firewall?

 

Bigger picture.

 

find some sheet metal you can use as a patch and replace it. Or go to a junk yard and cut that out of a car. or you could always clean off the rust buy some por15 - expensive stuff, and coat it and it will never rust again but you will still have the pits from the rust.

 

If it was my car, I would cut out all the rot and make a small patch panel yourself. Then just weld it up, paint it, and call it a day.

It looks like you only have one bend there, and it's not even compounded, so it should be pretty easy.

 

definitely cut out rust and patch in with new, welding and grinding is gonna be the only way

coat the hell out of it with body coating when finished, then paint

 

Is this a normal problem for F-bodies?

 

Not sure if it's normal, but I can tell you mine had it. Just fixed it a couple weeks ago.

 

The drivers side is way worse. The inner rocker, part of the floorpan, and part of the firewall are rotten.

 

That's weird how that works. My passenger side needed three decent size patches, but the driver's side was perfect.