It is more than 30 years old, so many insurers won't take it on as a new policy.
It is more than ~30' long, so many insurers who deal primarily in cars and homes won't take it on.
You're a new owner with limited credentials and no past ownership of a similar vessel, so again many insurers won't take it on.
And the boat may not pass a survey--so MOST insurers won't take it on in any case.
It may not be feasible but in some states you can post a bond in lieu of liability insurance on a motor vehicle, you might ask your state insurance department. Meanwhile, you need to make it a priority that the boat can and will pass a survey 100% and as soon as possible.
If there is a local USCG Aux or Power Squadron, you might ask them about membership and insurance, members often get a discount. Getting credentials (ASA tests, etc.) may help you. Or try IMIS, IMIS Home Page ~ International Marine Insurance Services
they're professionals and can probably put you with some legitimate carrier, or tell you what has to be done to qualify for one.