I've always used State Farm for all of my vehicles. I had a show car type policy on my 87 GN that had a $25K valuation on the car....of course I had an appraisal, copies of all factory documents, list of aftermarket parts with replacement costs, etc. With my T, I made sure they have it listed as a turbo Regal, not just a standard V6 Regal coupe. Whoever you get insurance with, make sure they put it in writing that they show it as a turbo Regal/GN, not a Regal coupe. Couple of people on here have gone through hell when something happened to their car and the ins company tried to say they had a regular Regal coupe, not a turbo car.
BTW....paying $74/mo full coverage for my T. I've also been with the same ins agent for 15 years now, so that helps a bit.