Yeah, after we learned the '91 DS was shooting at Greystone, but before the series debuted, I bought a VHS copy of
The Disorderly Orderly (because SG had mentioned that the Greystone estate had been used extensively in it) to see what it was like inside. I was disappointed, though, to discover later that many of the interiors used for the movie were actually sets and not real rooms in the house.
As for the mural, it would be fascinating to know why/when it was painted...