There are many significant issues with assigning value to any non-standard construction. First, obviously all real estate is local. I spent my career in a very LCOL area, and weathered the great recession, from which my market never recovered, so my numbers would look positively ridiculous in your market. Second, values are often driven by the bank. If it doesn't appraise on paper, even from blueprints, for many (most?) it's a project that will never even get started. My gut feeling however, is that building a really solid place, where all the additional funds are directed to the "bones" of the structure and mechanicals of a home, is probably a 15-20% bump. This would be a top to bottom upgrade. Poured foundation, top grade drainage, rubber exterior coating, spray foamed interior. Framing with I joist floors, Advantech, fir plywood sheathing, etc... Mechanicals to commercial standards, high level energy efficiency in everything from insulation to windows, doors. A fifty year roof, fifty year siding, etc..
I didn't know that anybody in the world of TV construction had an issue with ceiling fans? Kind of like odd. But remember, you are talking about a guy who looks at a wreck and says "I need six weeks and seventy grand to make this a palace" Cough, cough, me muttering "Bullshit" under my breath.
As for older places. I have one now, a mid-century modern ranch in a "To die for" location. That said, owning something like this is like getting handed a pillow case full of something that's wiggling around. It could be kittens, or snakes. You never know until you are the proud owner. In my case it turned out to be exterior walls of plaster on block, with a brick exterior. Durable, but totally unsuitable for a mid-atlantic climate. Much of the attic is insulated with 2" thick 1955 era. "pillows" about 4' long and 2" thick, They are made of craft paper with a thin piece of fiberglass insulation inside. They are as close to useless as it gets, and they crumble to little bits as you handle them. When it comes to galvanized plumbing, it tends to be a lost cause after half a century of use in most locations. The best bet is to tear it out. PEX is very DIY friendly, and glued CPVC is stupid easy. The most important part of buying old to really old homes is to have a really knowledgable pro. on hand to tell you if it has any deal breaking issues. You don't want to be dropping tens of thousands in rescue work for failed foundations, total mechanical replacements, or other real big issues, since it's all money down the drain. It might need to be done, but it needs to be completed and paid for by the seller, not you. Good luck.