For what it's worth, a trick I've used to see if old paper is worth the trouble is to take one full sheet, unexposed, and develop it. If there is a tonality to the emulsion side - toss it. Next, with clear, (unexposed but developed) film in the enlarger, expose a test strip for min. exposure / max. black but before you develop it cover approx 1/3 lengthwise and turn on your room lights briefly to make sure its well and truly fogged - then process as usual. If none of the enlarger exposures give you the max black of the heavily fogged portion then forget it for any images with strong shadow detail. If you can attain max black under the enlarger with film base then the paper's usable. To use the paper you'll need to do the max. black test anyway. I keep finding or getting given paper and this is what I've found useful. Until you prove otherwise though I wouldn't use it for your next exhibit.
Hope it helps.