I would say yes.Most of the GNs and Ts that are being parted out are not low mileage cars so most of the interior parts are gonna show some wear.The hardest to find in mint cond.would prolly be seats, door panels and steering wheels which can all be reupholstered.But will it be a perfect match??Another issue I've had is buying used stuff sight unseen.One guys version of mint or excellent condition might not meet my standards of mint or excellent.I would recommend buying at Carlisle PA or at a Buick event where you see what you're getting.Of course some basic stuff that's not GN/TR specific like A pillar trim,door armrests,other small trim pieces etc. would be easier to find in mint shape because it could come from most G-bodies not just a GN.If you do find a mint interior out of a low mile GN you will pay dearly for it.
If you need upholstery work done I found a guy in Southington, rts 305 and 422. He is redoing my drivers seat right now, and he is reasonable. Does very good work. Tell him I told you to call him.
G&H upholstery 330-898-7573 George
Tarey D.