Dear Moving Target
I actually have done these. Question 1. are you doing aclearspan? removing all joists? are you digging down further? These are the key drivers....also, depending upon age the enviromental costs...
As others mentioned below, materials are key, but not as key as above. There are two main decision points. Do I keep the existing layout and staircase or not? DO i did down or not. The "finishes" can range 50-90/sq ft....however, center city guts vary widely.
On the 1900 block of waverly, 1200 sq ft homes,I have seen $60k spent (kitchen, baths, windows, heating, high velocity a/c) ....and I have seen $180k spent.
Particularly in center city...are you in the historic district? You exterior costs will triple. Windows must be approved (usually Kolbe and Kolbe) but others also acceptable. Your gout/brick will be picked by Randal Baron at the hostoric commission, and a Tin vs Flat roof are very different cost points.
If you'd like to discuss this further, please give a ring at 267 312 6221.
If you are already working with a real estate agent, then discuss this further with them.