We only have the Minnesota Sanborn maps and bought them. The last time I talked to the rep, he said that they were going to turn the data into GIS (that was an awkard sentence but I think you know what I mean). Anyway, they were going to charge extra for it - our Sanborns barely get any use and I never did follow up. I'd check with ProQuest and see what gives.
Pam Enrici
Geography & GIS librarian
Univ. of MN., Duluth (on the now warmer shores of Lake Superior)
P.S. I figured you checked with UCLA but maybe UC Santa Barbara might have done some work (it's been a long time since I worked in California - I was an early member of WAML) and I did my BA and MA in Geography at UCLA and we headed up to Santa Barbara to see what they were doing. Have you contacted ArcGIS?
Anyway, good luck!