I agree that anti-fogging agents aren't going to do a lot, except lengthen the development time. The fog you've got is real, caused by the combined action of heat, cosmic-rays and other naturally occurring radiation over time. It's just as if the film had been exposed to a very weak light for 15 years. Fast films are more susceptible to this type of storage fogging than slower ones, and to make matters worse there's a thing called latent image regression. This means that the image on the film begins to fade from the moment the shutter closes, taking away the most weakly exposed parts of the image first. In other words, whatever you do, the shadow detail in those negatives is gone for good by now.(posted 8979 days ago)I had some Kodak High-speed recording film(1000 ISO) that had been in storage for a long time, and nothing would get rid of the high fog level. Kodak used to publish the formula for a developer specifically for high-speed films that were prone to high base-fog, I think it was called D65. I even brewed some of that up, with minimal effect.
I'd go for a vigorous developer without any additives. Perhaps using your Rodinal or HC-110 at above normal strength, but I can't give you specific time-dilution recommendations, as I don't use Tri-X.