So I’ve since blocked off the third floor on one side and rented it as a 1 BR for now. but when the other side leaves eventually I’m starting to lean towards raising the ground grade 28” so that the total drop is less than 20’and then I’ll knock down some walls and make the whole 3rd floor attached only to that last unit so that the whole area can use the stairs and that window as second egress. 

Also, the city's building code could be different as far as the required fire rating for party/shared walls, etc, thus the construction costs could be higher.

I got future walls done with wood panels as well as paint and wallpaper put up.What was the outcome?

Quote from @Jaron Walling: We're still renting my first property from 2018, have cash-flowed every month, and "lost" every dime replacing the HVAC this year.

The has been a lot of cases where the rehab was done to make it look beautiful to the buyer but everything behind the walls or where eyes cannot reach is done incorrectly.Even big new home builders do this kind of shady business where it comes to a point it is necessary to order inspection for new home builds in US .

Is there any place within the unit where you could add a through-the-wall A/C unit such as a ductless system or a window unit in a wall sleeve? 

I understand a duplex may have an Accessory Dwelling Unit (ADU).The objective is to get a permit to change the windows, put up siding, and add a fence.  

Remember, once the foundation is fixed (and it never is), you have to fix the superstructure items that were thrown out of wack, starting with load-bearing walls.  

Unless this is a wall oven, most ranges are a standard size.

How are the foundation walls, basement/crawlspace framing, HVAC/heating & cooling, roof, windows, elec.?