Correct finish/color for these parts?

I just looked at mine and it appears like the top half is body color and the bottom half is black. I guess it was black and they installed it before the painted the body so the top got the color of the car
The correct battery tray for 75(and probably 76)is a bit longer than the earlier trays by several inches. This was to accommodate a new larger capacity battery for those years. They’re rather hard to come by so if your car has one it’s either original to the car or someone went the extra mile to track down the correct replacement. None of the aftermarket guys currently make one.