Long ago there was this site IndiaOverland.com -However now unable to get it on the net - just found their address -
"IndiaOverLand Pvt. Ltd., 2nd Floor, Atur Chambers, 2-A Moledina Road, Pune - 411 001. INDIA Phone No. : (020) 6137177 / 6130941 Fax : (020) 6130575 E-mail :
info@indiaoverland.com"
They had wonderful info/maps -Being Pune based you should be able to contact them- Hope this info is useful -
PS - I have been dreaming of doing this trip for a long time!
If you dont get the map -let me know I search my hard disc/ cd's for it at home.
Rgds