[DeadheadNM]

Here's my take: PO installed the upper trim but didn't do too bad a job. The 2x stick tape is how 71-72 trim was affixed in some spots (unlike 70 and earlier) and the new tape is awful. That screw on the door pieces is correct, GM style. The splices on the rear segments are indeed how GM (and now aftermarket) made the trim. The rear piece on a pickup does not parallel the bed but slope very slightly downward. See my K20 build link in my signature for a factory example. Rear trim that is straight rather than sloping is a common oversight folks make when adding trim (the paint stripe was also sloped).