Both the period map of Antarctica and the Dornier Wal blueprint will by roughly 18" by 24" and printed on 100 lb. acid free uncoated paper. That was the best stock I could find for reproducing the look and feel of the real thing.
The flyer for the expedition's departure ceremony will by 9" by 12" and printed on 100 lb. paper with a matte finish. That's a bit heavier than a period handbill, but it should make mounting it easier for anyone that pursues that option.
The Hobart, Tasmania postcard will be, well, a postcard. Standard postcard size printed on 13 point uncoated cardstock.
With the core items finished things are almost ready to go. If there's anything else you'd like to see included now is the time to chime in.