If the house is burned out and requiring vast work already, why not cut a new set of stringers & treads?
I'm thinking this will definitely have to be part of the design. I'm conducting a demo that will leave only the poured foundation and slab in place. This will allow me to send my stair manufacture an elevation that includes any built up floor measurement. I'm still stuck on how to get the rear entry door to match the built up floor. Do I raise the door? If so, this will present a new condition on the exterior and I would be concerned about water infiltration.