Concours and Dennis Carpenter both have re-production floor panels. They may need some work after you get them but they're fairly close.  

I started to patch the holes with some 1/8" sheet I had laying around but it was so rotted that I was burning through the sections I was welding too.  So, I got pissed, grabbed a hammer and started swinging.  Now the floor board is in a pile under the car in the driveway and the 1/8" sheet that's in there looks like hell.  I need to cut it all back out before I mock up the new panels.  

Did you need to use a bead roller to strengthen the panels after you cut them, or was the 18 gauge enough to hold?  Also, did you do a couple welds and then seal the joints or did you do a continuous bead around the whole panel?  I'm thinking after I get this fixed I'm going to power wash underneath the car while the trans is out, and spray on some rust treatment and then some undercoating of some type.

Thanks for the help.  - John 

I didn't use a bead roller or anything.The 18 gauge is stiff enough when you're using a lot of small pieces.In order to get all the contours and curves somewhere near right,I wound up with a couple of dozen pieces.I welded almost all the seams completely.Any seam I didn't weld completely,I sealed with caulk.I then primed and painted the whole thing.With insulation and carpet on it,no one will ever be able to tell it's a backyard repair.

Good Luck!!!!