try Luminos for graded mural paper.
fwiw--they used to make fiber based murals in-house where I work -- we still have several rolls of paper left over ...at any rate, most of them are either the Kodak Mural paper--this was sorta of a single-mid type weight fiber paper with really good wet strength, for hand processing. There are also rolls of Ilfobrom and Kodabromide--as well as RC Multigrade III, and at least one of Kodabrome graded RC, which is only maybe a few yrs old, but would be discontinued now. FWIW, with the exception of the Multigrade, the others are all graded.
the paper sizes are usually in the 30-42,48 inch width range with a length of 100 feet. You may be able to find some 52 inch widths, but probably not in fiber....
*just checked the luminos site, and yes they do have 51 inch fiber. so there ya go--now you just need about 2-3 5x9 foot sinks....
hope this helps