The flex pipes in CA cars still appear fine, and might be stainless steel. My down-pipes show no rust. I have one off my 1985 CA car (won't fit yours) and it has no internal corrosion either. You might get just the parts down to the bottom front flange (get mating flange too), then any muffler shop should be able to do the rest. That would keep shipping costs low. For factory parts, I know P-P does/did carry the muffler-pipe-resonantor. One way to get junkyard parts is
Row52 | Find recycled automotive parts from self service auto recycling yards!, find a car in a yard and put in a request to independent pullers. But be clear exactly which parts you want, year, etc. (and not 1985 CA). But be professional and don't hem & haw, spin people up then change your mind.