Joel,
Marty remarked on the Central Vermont's newsprint operation. For several years I have been reading the Boston & Maine list, too (BM_RR). If you search the archives there, can't imagine you won't find paper mill postings.
Model Railroad carried a detailed, two-part article on a New England paper mill. Perhaps Andy or Marty will correct me if needed, but I recall it centered on a B&M serviced industry at Berlin, N.H.:
* An industry you can model, part 1: Papermaking and the railroads
Model Railroader, October 1998 page 100
("MCGUIRK, MARTY", PAPER, PROTOTYPE)
* An industry you can model, part 2: Papermaking and the railroads today Model Railroader, November 1998 page 90
An industry with great kitbashing potential
("HEDIGER, JIM", PAPER, PROTOTYPE)
If my memory serves me well, Marty presented an N scale layout based on this mill, Jim an HO layout based on same. (I saved both articles, came across them recently, but think I can find them now? Nooooooo.)
I don't recall its name, but the printing plant just 10-12 miles north of Kalmbach's Waukesha offices is monstrously huge. Man, it's big, big, big. But, you're looking for a 1950s operation. I think the above MR articles would help you a lot.
Brian
Brian Chapman
Evansdale, Iowa