"Regular" insurance is written as Actual Cash Value. The trick is determining the ACV. A lot easier for the GN guys, as there are a lot of them out there and on the market, with easily found examples of nice ones to use as examples of value. Lot tougher if you have something like Cali's wagon, a pristine 78 Malibu, or pretty much anything outside the "mainstream" collectibles because there are so few comparable vehicles to refer to.
If you want more than NADA in the event of a total loss, and are using a "regular" insurer, you NEED to get an appraisal from a recognized / reputable appraiser (preferably state-licensed and understands specialty cars), and follow it up with an agreed value policy that will pay the specified value in the event of a total loss.
There are policies that are sometimes referred to as stated value, which means they will pay the ACV UP TO the stated amount.
Also need to read the policy, and review it each renewal period. I have heard of policies that had a feature that depreciated the value each year, possibly leaving you short in the event of a total loss several years down the road.
I get that for lots of people, these specialty insurers are a good resource, especially folks that mainly show them, but dangit, i like to drive mine as much as I can