I start exposing unknown or long expired bulk film stocks by shooting a reflective b&w target found in old Kodak dataguides.
I light it evenly, and use the grey card on the facing page to establish a metered vaule for an assumed speed. If it is thought to be say, 400, I will shoot it at 50, 100, 200, and 400. I have never found old film to gain speed.
I shoot three sequences this way, and snip the shot film off the camera in the darkroom and load to a reel each time I shoot a sequence.
Then I have three short reels to fiddle developing times with.
If fog is huge, I will add benzotriazole as a restrainer, and then re-shoot, because it will change the effective speed of the film.
Hope this generic method helps.