I've never raced in SVRA, so take what I say with a grain or three of salt. But I don't think that your car needs to have any particular history. You can make up whatever you want to make your car more interesting :-)
It just needs to conform to the specifications called out in the class you want to run - G3, G4, G5, etc.
Matt Merritt prepared a car to run in SVRA and later sold it. Perhaps you could get in touch with him?
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