Doubt there are any aftermarket pipes out there. Best bet is to have a shop bend everything up to fit the car and have them install. Devon
I think you can buy TA’s mandrel bent A body exhaust (and maybe downpipes) and then add straight pipe for the extra wheelbase and longer rear quarters. I’ve seen a few Wildcats that look like what was done. Patrick
I haven't used them but they say Jay Leno does. https://waldronexhaust.com/product/1965-74-buick-v8-dual-with-2-mufflers-2-resonators/
Try Gardener exhaust in New York. They did my exhaust on my 70 Skylark 455. They design their exhaust to Buick factory specs. The owner took my order and is a super nice guy. Vet
Second on the Waldrons. Tubing upsize available and a couple muffler options. I've used them for several Wildcats, good jobs.