Just this afternoon I communicated with a friend that bought a new, white P1800 and still has it. She has only owned new Volvos starting with a 1959 PV544 Sport. The 1800 is the only previous one that she kept. I have known her since the 1950s.
Even though I do not believe that AOAI was founded there, the "first chapter" may have been in DC because there were a lot of early Avanti people there.
I believe that a complete set of carpeting is 14 pieces. I think that is what you are looking for, but the question only refers to trunk carpeting (not all, including trunk carpeting).