Perhaps, Gram wrote the song is about the original City of Sin; San Francisco.

This may help you to understand the significance of Joshua II, The Nudie Suits, etc.-

http://symonsez.wordpress.com/2010/04/18/1906-san-francisco-quake-day-after-curse-by-nudist-prophet/

Perhaps, the 31st floor is a testament to the 315 ft tall "Call Building" which was the tallest west of the Mississippi River in 1906. 315 ft would be about 31 floors in today's calculations, but the building only had 12 floors according to historical accounts....

Again, these are only my speculations based on the facts, details, and historical accounts of the original City of Sin!

Time to fire up the Harley and take a ride,
Dblugras