Is it OK to upload a build based on a real life structure, such as the Amityville Horror House?

Of course it's okay. I personally enjoy building historical houses. If you use floorplans be prepared to adjust them as needed, a lot of them have useless closets which you won't need unless you want a master bedroom with a walk in wardrobe. I found if you follow plans exactly the house ends up looking too big so try to scale it down by about a quarter or even a third until it looks right. Use furniture as place markers as you build so you can work out sizes.