Thanks for the update. What's the plan going forward?
It sounds like what we’re asking for is difficult to accomplish (modern floorplan inside an old style structure)
Not really. I'll repeat what I said above.
Try designing this as if it were a remodel of an existing smaller older house, or look to well designed older homes in a style you like that are larger for inspiration.
When I say a remodel, draw the old house as it would have been built, then imagine how it would have been transformed over time into what you want today. Have you ever watched This Old House on PBS. Many episodes on transitioning an old house into one for today.
Q