I had a friend who took his Chevelle in for exhaust.

Car got stolen from the exhaust shop with pretty much all the documentation of parts & labor in the trunk. Why it was in there, I do not know.

Insurance for the shop didn't want to pay so he went to court and won a judgement of 50K for the car.
They appealed and he lost. In the end he got nothing, no car no money.

I would carry the extra insurance if you already have 30k in the car. Just to be safe.

Not good.

The reason we should not rely on the shop keepers insurance is because it is a liability policy that covers HIS liability. He COULD be considered liable for thing that happen to your car while in his care like fire, theft, falling off a hoist, something falls on it, etc. But it doesn't mean he WILL be.
Problems are that liability insurance only pays for actual cash value, not replacement cost. And his insurance company doesn't give a hoot about you. They can get some hired gun appraiser to put a super low actual cash value on your car because it is apart. Or they can flat out deny that it is the shops fault. He could have some cheap class C rated company, most of whose modus operandi is to deny, deny, deny, and only pay if they are forced to. Your only recourse is to sue them.

After an insurance rep quoted me chapter and verse out of the WV insurance codes, and said if I don't like it I should lobby to have the laws changed, I decided that sueing an insurance company over car damages is a fool's errand. They made it clear right up front that I had no chance of winning.

So, restoration insurance will be purchased with a stated value on the car that increases over time. That way if something happens I get paid, and my insurance and the shop's insurance can fight it out.