SR Laprade came in a 250. I don't know of any 80s euro posts that came in long sizes. The only euro post in common use was Campagnolo. Occasionally you'd see Zeus, Galli, Ofmega, etc posts, but they were sized the same.

People didn't use long seatposts and small frame then, which is sort of fundamental to your question. If you want to use vintage correct parts you'll need to fit a frame like they did then. Though frame sizes got smaller in the 80s, they were really only about 2-3 cm smaller than what would have been used in the 70s "handful of post" era. Compared to now frame sizes were big and top tubes didn't slope.

I agree with Otis, Nitto is your best bet.