Also make sure you can get it out of the door of your shop.
I did one this large about 5 years ago. What a pain.
Is the poster of any value?
Mine was an old advertising poster that the client paid $12,000 for.
We built strainer, backing, poster, acrylic package and sealed it with heavy duty clear packing tape. The 4 rails were designed so that we could bolt them together at the clients home.
The whole thing weighed about 200 lb. and was hung with z-bar. It still looks great and has held up well over the years.
The client has had the room painted and the painters moved this monster with no problems.