Ha, ha, ha, I cannot stop laughing.... Of course everyone is correct because the unpredictable nature of "Old" film is about the only thing one can say for sure. If I had several B & W rolls, I would shoot one roll, bracketing from measured exposure, and three stops either side. Do about seven exposure, then repeat the sequence three times on a 20 exp roll. In the darkroom, cut the film into three pieces, with the bracketed exposures on each, and develop at normal, plus 15% and plus 30%. And of course you will have 21 exposures to choose from, thus you will have a point of reference for the other rolls.
Color does something strange in that in the 1960's and 1970's, the old color film would shift its sensitivity, but unfortunately the Red, Blue, and Green dyes would not change the same way. So, the shadows might be different than the mid tones and the high lights almost any color. None of this is really correctable as the various locations on the film would not even change the same.
So, I hope you had fun! Haven't shot film in years.... and miss it.