I would test it out to see what the new speed is by conducting controlled exposure like I did with this Kodak Ektar 125 which shows expired 4/1992. Based on this I figured that it is best set at ISO32 so I have latitude on either side for best flexibility.
Years back I thought the lab we worked at did silver recovery on old film, back when when my labor was cheap and it just added to the every other month shipment to reclaim the silver.
the great thing about using expired photo products is
the randomness, and crap shoot that it might be.
the film may work as it did the moment it was produced
or it may do weird stuff. personally i don't mind the weird-stuff
i kind of look forward to it, otherwise photography becomes
just a boring exercise of technical perfectness, perfect contrast
perfect this and that ...
as a antidote, put a little wabi-sabi in your camera ...