many insurance companies will do 'stated value' coverage.
you tell them how much its worth (they may need to look at it) and then they do some math and give you a monthly payment.
Based on the conversations I've had with insurance agents here, I'd also recommend having an appraisal done... or at very least a stack of photo's and an equally high pile of receipts for parts and work. For my Fj40, I couldn't get a declared value policy because of it's age and because I was driving it to work. The insurance company claims the current plan covers full value, but from experience, they'll only want to give book value. If I have an appraisal done, it'll be concrete evidence from an independent party proving the value of the truck... until it's pretty (which may never happen) there's no point... because only a true gearhead will see the value of a well modified rig... most can't look past faded paint.
As an example, when a car took me off my 3 year old BMW F650, the insurance company only wanted to pay me 6k for a bike I had 12k into... claiming it wasn't very 'clean'. Because I hadn't washed it since it rained that morning, and it then was hit by a car, flipped end over end, slammed on the asphalt, and slid through the dirt... also it had about 25k miles on it (even though the motor wasn't fully broken in).
The more Ammo you have for a fight, the better (also don't piss off the local shop/dealership the insurance company will ask for a value).They'll let you ensure it for as much as you want to get your money... but only pay out what they decide it's worth... regardless of how unreasonable that may be.