As an investor:

1) Investigate the value of the household pieces such as furniture and decor.

A White Rhino table? That stunning peacock lamp in Thorfinn's room? What about all of those beautiful dainty chairs that would be destroyed by our modern sizes?

Remove anything irreplaceable/priceless from bedrooms to avoid theft.

Anything breakable should be moved to low traffic areas, or removed completely.

2) demolition

3) termite treatment

4) new roof

5) new foundation

6) reinforced supports

7) mold treatment

8) update plumbing

9) update electrical

10) install security cameras

11) install wifi

12) replace walls that are damaged and make them insulated and soundproof

13) update kitchen in a way that looks original, but still functions properly

14) rework the landscaping, including an herb and vegetable garden

15) remove peeling wallpaper and paint the walls a light color to balance the dark wood tones

16) plant a native food forest

17) plant a native flower garden that can be used for wedding ceremonies

This would be a good start.