Be sure to compare 'basic' coverages from Hagerty or whatever specialty insurer you are considering. Hagerty, who I use, plugs in their bottom end coverage for Liability, $25,000 per accident, Liability PD(property damage) $25,000, Medical, $1000 per person/per accident, and uninsured/underinsured $25,000/person or $50,000 per accident.
Even $100,000 of coverage on the vehicle doesn't mean much if a person is found liable and the basic coverages don't cover costs of an accident. Lawsuits are expensive and a settlement could force the sale of the collector vehicle.
I suppose there is a good balance, depending on other personal factors, of auto insurance coverage and also carrying a personal liability 'umbrella' policy, but I don't know enough about that to fill a thimble. :brickwall: