From a first hand experience, other than your parts, what else was taken? Were all of the parts new, look new or worth money? Chances are slim that it was a select, targeted theft.
As far as the theft at someone else's business, you DO NOT claim any of this on your insurance. Since your vehicle was in possession of another party, they are FULLY liable for any theft or damage.
The business where your car was has to reimburse you fully and totally. Their insurance police will cover your entire loss, not adjusted loss, actual loss. If it does not, you can and should file a motion for the balance from that business.
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1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.