Greetings, Matt. While I personally have not the information you are seeking,
might I suggest that you check out the Great Northern Yahoo group. There are
members there who very likely have exactly what you're looking for-as I recently
read several posts there regarding that very subject. Try www.gngoat@yahoo.com
'Tis a good place to go anyway for any GN fan.
Matt,
Go out to Terraserver and you will see some track stuff in Somers:
http://terraserver.microsoft.com/image.aspx?T=2&S=11&Z=11&X=1766&Y=13323&W=3&qs=%7ckalispel%7cmt%7c
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Hope that helps - using the old USGS map and that arial photograph should get you in the ballpark.