Ames Performance sells upholstery for the Tempest, which also fits. Of course, none of those options will be correct.
It cost me just under $900 for door and rear quarter panels for my 67 Delta from SMS, so that number is accurate as of a month ago. I also got all the turquoise upholstery materials and headliner for the 67 from them as well. Certainly not cheap, but where else are you going to get this stuff. Despite horror stories about service, my materials arrived exactly ten days after ordering. Door panels are supposed to be done in another month or so.