I have a half freezer full of Polymax fiber paper... 8x10, 11x14, 16x20, F and N surfaces. I moved, lost my darkroom, and probably won't go about building another. I'd sell this to you if you're interested. I could test in a makeshift darkroom (blackout windows in a bathroom).
BTW, I don't suppose you went to the Naval School of Photography back in 1969?
If it's been frozen, it's likely good. But I have found most of Kodak's 1990s-2000s paper has now gone to mud.