First welcome to the site, most vendors sell the panels you are looking for. But if that area is rusted out, I'm guessing the rust issues are far more deeper then what you can see. One area that also gets rusted out is where the front fender connects at the bottom and you have to make a replacement panel to repair that area. Also it most llikely has effected your floor pan area somewhere. Here's another vendor who has the panels also (Ground Up). Post some pictures when you can. Good luck on your car and again welcome.
Ray
http://www.ss396.com/mm5/merchant.mv...ct_Code=RCP-7L
http://www.ss396.com/mm5/merchant.mv...ct_Code=RCP-7R
http://www.ss396.com/mm5/merchant.mv..._Code=RCP-1419