Tom,
I purchased a one piece die cut cardboard headliner from Jim Carter Truck for my 1941 Chevrolet. The sales representative stated that the headliner was cut to fit without alterations. Well to make a long story short, the installation attempt was horrible! The vague instructions to spray the cardboard with a 50/50 water/ammonia solution made the cardboard limp and very prone to creasing. Making the complex bend in the rear corners will be tough to make presentable. I think the originals were steamed and formed in a press, something a hobbyist would not be able to do. The fit/finish of the cardboard headliner is terrible. I asked the Jim Carter representatives for more information on installation and they gave me a link to a Stovebolt site. In that site, the guy stated that after attempting (and ruining) the cardboard headliner that he went with the formed ABS or fiberglass version. When I asked the representatives at Jim Carter about this, and if anyone had ever successfully installed a one piece cardboard headliner, the reply was that they had sold hundreds of cardboard headliners. They did not state that they know of anyone that has satisfactorily installed one. The ordeal dealing with Jim Carter and their refusal to offer real advise or to credit the cost of the junk cardboard headliner towards one of their fiberglass versions has made an ex-customer out of me. There are other vendors, and I will spend my money elsewhere from this day forward. In my opinion, Jim Carter (and others) are selling a product that is useless and they won't admit the fact.
All I can say is good luck, and let me know how the fiberglass or ABS headliner fits.