Restoring duplex into SFH

[Josie Zimmermann]

I am looking at potentially restoring a 1915 brick 2-story home. It was converted into a duplex with exterior access (exclusively) to the upper space. My hope is to leave the exterior access and simply reopen the original wall/case and add back a few stairs to that landing. The home also has two heating/cooling units and two meters. Not sure if there is a benefit to keeping/using/removing.

Just wondering if you all have any advice or experiences relevant to this type of renovation. Thank you so much!