Was responding to a a related question on another site so like in the past wanted to share the same information and pictures on our site.
As you may recall the interior paint was applied before the exterior color/paint was applied. Because of this areas that were painted interior colors needed to be protected during the exterior paint application using tape and or masks. To start this thread here is the response posted elsewhere. Will be following up with details of other areas of the interior without all the interior parts attached to help others trying to replicate/restore these areas of their cars.
Where and how the paint got applied depended on how caring. patient and careful both the masker and painter were on that car. He location or area that the interior door mask covered varied slightly depending on where the masker put it and the adhesive (tape or mask) edge. Typically it was much like the other two plants where at the front and rear of the door the paint edge followed under where the weather strip would be glued but at the bottom the line moved inward and away slightly from the metal weather strip channel on the bottom of the door. If the masker didn't press the mask well enough the mask lifted and the exterior color could travel in side the mask for a small distance or in some cases the painter didn't been over much and some of the bottom of the door would only receive a light coat of overspray and later rust. Remember the interior of the door was painted interior color before the exterior color was applied.
Here are some examples of the extremes. The bottom pictures illustrate the most common and typical IMHO results where everyone was doing their job as expected
Pic #1 top picture shows where the mask was not attached well and we see body color introduced under the mask
Pic #2 On the top the masker applied the edge allot closer to the weather strip channel than normal but still leaving the channel exposed to the exterior paint application on the inside surface. Bottom picture another paint "blow out" under the mask edge
Pic #3
