STARTMAP is the first fieldfile executed from the engine. On load, it runs STARTMAP, then jumps to MD1STIN.
Now we need to overlay that over field backgound to see how well we line up. Remeber, FF7 field files run in a strange resolution. You may have to re-project with the top and bottom of the viewport "squished" to get the edges to line up.
On the subject of "The stairclimb from heck"
I'm playing FF7 again, this time keeping an eye out for odd things that the field files do. The perspective of the stairs look correct. I thought it was some kind of isometric projection. It looks good actually.