No capital improvements? While possible, it's highly improbable. I would expect over 40 years you're replaced the central A/C at least twice, and have replaced the roof at least once, if not twice. What about the windows? I doubt it still has the original jealousy windows that may have been in the house at the time of purchase. Has the hot water heater lasted the entire 40 years? You never updated the kitchen or bath? All such expenses add to your cost basis.
