Car insurance on Hemi swapped cars

Has anyone else had a situation where they restored and Hemi / 5-speed swapped a slant six automatic car, I mean rotisserie, no bolt untouched refurb, and you contact your insurance company to add it to the policy and they say the average value for the car is $9000, so we cannot insure it for much more than that?

Do you have to have these "restomod" cars appraised to get them insured for a more true value?

Thanks.