I think depends on a few things but the difficulty is honestly pretty relative. If someone still remembers the high yield info from Biology, Biochem, and Chemistry, they can probably spend time taking notes based on an official review guide for about a month, taking 3-4 official AAMC mock exams prior to the real deal, reviewing all the questions they got wrong afterwards and making notes to avoid the same mistakes.
Even then there is a luck component and risk of not knowing certain things on test day, but up to date practice can minimize the risk of that.
If OP hasn't retained familiarity with the high yield topics or they can't free up good time during that month, then it is risky. But treating it like a mini dedicated was doable and decent practice for STEPs imo. The range of 513-517 might be possible depending on what appears on the exam and how much their practice covers.