I don’t think you’d have to find a special company, but you’d have to find out if Allstate and State Farm would cover it. They might; but they also can decline coverage on such an automobile. Allstate and State Farm are, as I recall, “direct writers,” selling fairly standard insurance packages through their own agents, who don’t necessarily have the authority to accept business for special or unusual policies. Remember, any insurer, including those above, doesn’t have to take your business.
Many broker-market insurers can write a custom policy, as opposed to an “off-the-shelf” policy, for classic/rare/special-in-some-way automobiles. The best way to find out who might is through a call to an independent insurance broker or agent. Even if they don’t deal with insurers who underwrite such policies, they would have an idea of which insurers and brokers do, and would tell you how to go about getting such a policy.
In short, any insurer may cover such a car, but it may not be under a regular (and regularly priced) policy.