1) I agree, that the street grounded the image, so I put it back in, and just tried to mask the "newer" items in the image that stuck out for the older concept I was going for. Helped me learn about layer priority as well when I tried replacing a few signs.
2) Since I'm not going back, not much I could do about taking a new picture to help make the buildings more vertical. But the comments helped point out the "transform" function, so I played a little with that as well. Couldn't get perfect, as I ended up just chasing my tail eventually, but do think I was able to improve it a bit without totally losing the fire escapes on the left side, which I really liked.
3) I also, just for fun, tried another aging process on the older buildings. This method kept the color differences, but played with the saturation and shading to try and mimic the older photos that had color but not very deep blacks to them.
4) I also tried creating my own clouds in the area I removed the top of the building in the back. Thought it might help mask the fill of new sky that was hard to blend.
Thanks for the comments. As this was basically an "exercise" to start learning the software, it was useful to point me in the direction to try a few things I didn't even think of at first. Still have a way to go, but it was a decent first step.....John