I know of two other cars that are L78 cars, built at the same time as your car, and were also dark green. One is a possible dealer modified car.
But your car has a different Special Order (F&SO) number (L229D) than the other two.
As a SS350 car, I would question that your car was dealer converted to a 427 car, especially that late in the year. They would start with a big block, normally an L78 so they could reuse the most components. And have the right engine mounts, heater core, radiator, etc.
Why the L78 cars have a different F&SO than your car is an interesting question - seeing that they are apparently the same color, just different drivetrains.