Bill, I've been a State Farm customer before and may be again - I always felt that I was treated fairly by them. However, you should be aware that under MOST "stated value" policies, the insurance company is not obligated to pay more than the actual cash value of the vehicle - regardless of what value has been stated and agreed to. Most insurance agents don't know this.
Check this page at an Insurance Broker site.
This is a real pain to me. I have a very nice 1983 280ZX Turbo that's worth probably $6000 to a Z-fan, but ACV would probably run about $3K according to an insurance company. I'm trying to find agreed value insurance but I don't have a locked garage to park it in, so I'm DQ'd by every company I've identified so far. I'm pretty frustrated. The folks at Hagerty were nice in their correspondence, but the lack of a garage was a deal killer for them, even though I live in a place where you can leave your garage door open and take off for a weekend and still not have anyone mess with anything.
I had some hail damage last year and I had to fight the Hartford (my current company, and one that is growing too expensive) for a month to avoid having them total my ZX for $2500 worth of work. That pissed me off considerably.
It appears the only option I may have is to get the car appraised, take a ton of photos and do my best to prove the value I know it to have in case of a substantial loss.