You are most likely going to lose a lot of the value in both the fact you are working with an expired domain and you are switching to SSL. You have to wonder if it’s worth it. This is something you need a number of variables to consider not just what the ‘score’ might be from sites like Majestic, Moz, etc but also an evaluation of the content on the site, how many years it was live before it dropped, the type of content, how it ranked, what PR it had, etc, etc.