I've been getting a lot of email and phone calls regarding insurance for vintage and classic motorcycles so I've dedicated a page to it on the www.vintage-rider.com site. You can get information on what the insurance companies will ask you and a fairly comprehensive list of insurance companies with their contact details.
You can get to the information by either going to the main page, clicking on the "links" tab or go directly to www.vintage-rider.com/insurance.htm
When I do my updates at the end of the month it will be on the navigation bar.
I hope this helps!