As somebody that inherited a similar mess, spent 5 years of their life on it, made a lot of progress, but still didn’t fully “fix it” in the end, let me caution

As somebody that inherited a similar mess, spent 5 years of their life on it, made a lot of progress, but still didn’t fully “fix it” in the end, let me caution you a bit before you embark on this quest. Consider the opportunity cost of cleaning up this mess. Consider the years of your life spent. The impact to your career. The stress. In my opinion, unless the compensation is legendary OR this is something you feel very strongly about taking on, you might consider taking a different and more fulfilling role.