This is a great start. I wonder if it wouldn't benefit from its own new texture.
I think we could save some triangles by getting rid of the 2 staircases we won't commonly see. I think the original building abutted walls and other buildings on those 2 sides anyway. So, copy the double staircase on the front over to the left side we see here, then get rid of the 2 staircases on the far side. I might be able to help with textures for the staircases. The game does have this:
Which would be verrrrry useful for the Wonder. Here it is on the Tachara: