Andy,
Insurance is tricky here in the States. Any guaranteed value policy is going to have restrictions on mileage (1,000 - 2,000 miles per year, I think) which is about 5,000 miles less than I drive my 1970 280SL. Almost every "normal" auto insurance policy is an Actual Cash Value policy, which means if the car is in an accident, every part will be covered, subject to a deductible per event, at replacement cost, which is most often an ebay price, or a mercedes dealer price, whichever less. If the accident is serious, they will research the market value of the car by using available valuation resources. Thus, I have countless dated pictures of my car, and a recent appraisal. (mine is a year old for about $60k USD). I have spent hours on the phone with the claims folks at the Allstate Home Office who have shared their methodology and I am comfortable with my decision. I did have a fender bender with my car and broke a headlight door (just the plastic) I got a check for $1,423.00 (and I have my own stockpile of AJ Headlight doors).
For my car to sustain $60k of damage, I probably won't be around to worry about fixing it. It is unlikely that the car will ever be "totalled" and the repairs would always be made to get it back on the road. If stolen, my appraisal and Hagerty/Hemmings valuations should suffice. And I can drive the car anywhere I want, for as long as I want.
As the 4th vehicle on my auto policy, I pay about $230 USD per 6 months, with no restrictions, $2m of liability, a $500 collision deductible, and a $0 comp deductible. So, I guess you have to decide how much you want to drive this beautiful car.
Hope this helps.
Mike Mizesko