Although the maps which I have been using to determine the location of the "Ripper's" attack on Ada Wilson (9 Maidman) are not very accurate (I used the one with the most detail, and hopefully greatest accuracy - see it here), the coordinates I eventually decided to use, according to Google Earth's ruler (and protractor) tool, are within a couple hundredths of a degree of 75 degrees, relative to the center of St. Paul Cathedral's dome.
I decided to try another approach to determining this location, by assuming that the private property lines on the SE corner of Mile End Road and Burdett Road haven't moved since 1888. (Previously, I assumed that road-widening might have pushed these lines further to the SE.) The result was a slightly different location for 9 Maidman, and it too measured precisely 75 degees, give or take a couple of hundredths.
The Nichols/Durward St. location, which appears to have been intended to be aligned with this vector, measures about 75.3 degrees. 75 degrees precisely would be a ways back in Essex Wharf, which for some reason is covered in considerable detail by various Ripper sites even though its only supposed connection is that it was across the street from where Nichols' body was found.