In Beyond the Rim there are stats for the Iso-One, however, it says that it is modified, but I am not sure with what. I would like to know how that affects the stats and hard points. I'd like to use something like it in a game but with some different mods. I am not sure if I just skipped whatever it states in the book or not.

As far as I know, there aren't any "stock" examples of that particular freighter. From just glancing at the stats, I'd say the turrets aren't stock (or at least, not all of them). Really, if it was me, I'd just eyeball it and go with what I thought works. YMMV