Alfaholics have a bluette/pale grey rear seat section for an early Sprint GT
here. The photo on the website is poor, however, but maybe if you email Max or Richard directly and ask really nicely, they might take a better picture of it for you. People usually recommend Re-Originals in the US for correct interior trim, but they can be expensive. Also consider Cicognani and Elvezio Esposito in Italy. I also believe there is a very good carpet supplier somewhere in Australia whose name escapes me at the moment. The early armrests are completely unavailable unless you have a verrry lucky find on eBay. Good luck ...
Alex.