Unfortunately there are no complete new floor pan replacements, however you can buy used floor pans. If you are on the west coast, the first company I would try is California Corvair, 951-284-3555, ask for Jeff.
http://www.californiacorvairparts.com/ The second company on the west coast would be LSCorvair parts, 310-534-3324, ask for Larry.
http://www.larryscorvair.com/ If you are on the East coast, call the Corvair Ranch in Gettysburg Pennsilvania, 717-624-2805, ask for Jeff.
http://www.corvairranch.com/ If you are anywhere else in the country, you have to pick either of these Left coast or Right coast vendors.