I was snooping around my old shelf at my house and found a old past HSC papers for 2u maths, from 1974 - 1995,
would it be okay to go through that? like would it be useless or useful?
They are still useful, I dont think the syllabus hasn't changed significantly over the past few decades. It would probably be more wise to do recent ones, but if you have gone through then, then go for the older ones.