The site is approximately 430 yards slightly northwest of my previous suggested location. There had been prior indication that the house was long demolished.
This is all exciting, yet sad news if the building will not be preserved. It is fortunate that we can now know the true location of the following January 1862 photographs, including one that shows General McClellan meeting with officers outside.
View from Google Earth indicating the original structure, outlined in red, and the approximate location of the nearby signal tower, also marked in red. Click image for larger examination.
Below, with kind permission of Stephen Masters, here are comparison
images of the structure as it stands today. More will be posted soon.