I'd take it to that inspector's boss (or the "head guy's" boss, if necessary), and request clarification as to exactly what law you have violated. Panteras aren't the only unibody vehicles out there, and they did pass FMVSS requirements for their year of manufacture. I do not believe that they can force you to modify the structure of the car so as to tie in with the "frame" (such as it is in the rear of the car).
Maybe contact your elected state representatives and plead your case to them. Your car getting thrown off the road is a hardship to you. Being non-roadworthy would devalue it, which may constitute a "taking". Your representatives may have some pull with your DMV, since they control the purse strings that feed the DMV. At least, they should be able to demand DMV answer the question of specifically "what law is being broken". You deserve that answer, at the very least.
I would not file a claim against the inspector, as I'd expect him to respond by doubling down on things to cover his rear. If he gets his superiors going on this too, then you'll be facing an even bigger hurdle, as they'll all be trying to defend their inspector's decision.
I'd try and take the stance that the inspector made a mistake that simply needs to be corrected.
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