David, without a LOT more information, it is very hard to say.
There seems to be a reasonable premium paid for solid, unmolested and very original Panteras. A slight premium also for Push-button cars, but putting a percentage on that is very hard since so few Panteras are easily comparable. If the car in question is a rusted, modified and repainted car then it being a Push-button won't be enough to save its value. I follow DeTomaso market prices fairly closely, but am no oracle. Ultimately the market decides anyway.
Mark
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