It doesn't necessarily answer your question regarding testing, but I have a fair bit of outdated paper in my darkroom that I'm slowly using up.
My method is to give the print just a hair more exposure, and after the print is developed, fixed, and washed, I use a pot ferri bleach and bleach back the fog until it is near paper white. I use a fairly dilute bleach, so that things don't happen too quickly.
It makes for a pretty nice print, and good enough where the difference compared to a print on fresh paper is pretty minimal.
The slightly lower contrast of the paper has to be accounted for.
Afterward I wash, fix again, wash, and then either dry the print or commence with toning in normal order.
I can't stand seeing paper go to waste.
Hope this helps a little.