the underneath and back side of the headlight buckets were they fully painted or just a light over spray of colour
Some where in between
Consider that there are allot of compound curves in the design of the head light buckets that year and the back sides were not masked off so as the paint was applied to the thin edge of where it would mount to the fender or where the bottom extensions were built into the bucket at the bottom all the paint that didn't go directly on those surfaces had to hit and stick to the surfaces behind them - considering the angle.
Here is an example of how nice the finish and coverage could be on the main surfaces. Corners, pockets and shadows would not be as nice.
Don't forget about the headlight black out detail also while your focusing on this part of the body