Thank you, Jon!
This solves my dilemma if I should keep the tank black or not when (and if) I decided to restore my '67 LOS.
I notice the water wall in pictures 2,3 & 4. I'm sure this was for overspray control.
I also see black overspary on the edge of the muffler in picture #4.
As for the reason to painting the tank, I wonder who made that decision to perform the step because it must have been tallied in the overall cost for a Camaro production being it involved a person, parts (spray gun and floor space) and materials. My guess it was applied for aesthetics reasons.
Mike