Worse than it looks--driver's side floor repair

I've been anxious to get back on the floor repair so I can button up the serious metal work and get this gal on the rotisserie.   Saturday presented me with a small window that I could remove the rest of the driver's side floor and start the fitting of the new floor piece and get it ready to install.   I started out with my pile of tools--both air and electric...

Not seen is the air saw and a few "persuaders" inside the car like my hammer and chisel and drill with the spot weld cutter.   After about 45 minutes of work, I had this pile of parts on the floor next to the car...

I'm one of these guys who saves all the pieces I've cut out until I know for sure I won't need them for a reference.  I've had the bad experience of tossing the trashed parts only then to find out I needed a reference dimension to install a bracket or drill a hole for a fitting.   The thing is, the parts pile is getting pretty big.  But that's what a shed is for right?...except the shed is already full of lawn and garden equipment and is basically my wife's "garage" since I've pretty much taken over 2 bays of our regular garage.   Anyway...

I cut the floor out in pieces so that I could preserve as much of the base material in the frame rails, rocker panel, and remaining floor intact.   With the exception of some trimming along the drive shaft tunnel, the hole was pretty much done.

I knew I would get back to that after doing some more cleaning up of the metal.  I took my 4" grinder with a heavy-duty wire brush and started cleaning up all the surface rust...or what I thought was surface rust.  I was amazed how I went from having a piece of the car that looked like it would only require a small patch here or there to an entire panel that looks like a slice of Swiss Lorraine cheese.

Some of the holes are visible with the flash...

...but with no flash, the light shining through the rust holes is major

The frame rail extension is in good shape.  A little cleanup and some POR-15 and that will be that.   Same for the transmission tunnel support (except for the cut I accidentally made while cutting out the flloor.)   Oh well....

I ordered the offending panel this afternoon.  Thankfully I can do the other patching without a major firewall replacement.   So in the mean time, I'll do my cleanup and paint of the frame rail and get the floor piece pre-drilled for the rosette welds.  Then I can finish up the main metal work.   I hope this will be it, but something tells me in the back of my mind that I better not get my hopes too high.