66 Chevelle... Should I paint rear panel or not?

[ORIGLS6]

A White '66 SS396 was the first Big Block I ever drove. I had a '65 Impala and took it to the dealer for a problem with the OD trans. The Dealer let me drive his son's "Demo" car; the Chevelle. Had it for two days. Fairly low option car, just Black buckets, no console, red stripes, dog dishes, L35 and a 4 speed. I can still picture that car vividly. No black on the tail panel, but I honestly can't tell you whether it might have been an early or late car.
The car made such an impression on me that I ordered a new '68 SS396 three months before my '65 was paid for! Had to make a double payment to finish up the paperwork the day I picked up the '68. Ah, the ignorance of youth!!!