This is looking down Webster Ave from Grant. The current DoubleTree Hotel is under construction in the background.
That's what I had and the view was closer to what you tagged.
You're totally right - when I loaded your, it was showing a totally different pan yesterday. I think it was a glitch. However, the view is from Grant Street, and your is from a little up Sixth. You can tell by the perspective on the DoubleTree building.
Also, regarding the description from the archive, the view is clearly not from the roof of the William Penn. More like the 6th floor. :)
Regarding the two buses visible in the photo, the one in front is an ACF-Brill model C-27, belonging to Pittsburgh Railways Co. The other is a White, model and owner unknown.