My OEM 67 one family Dart did not come with the black cup that locates the hard board cover. It may have been a Plymouth thing or 68 up?
Maybe it's the wrong one?
Head rest were an option in 67. You could get drivers only, pass only or both
There is a kit you need to buy to retrofit the seat to accept head rests. The 67 headrest is unique one year only. They changed dramatically in 68. Iirc the rod of and the spacing is different 67 to 68.
You probably...
Another way to go to find leaks is with a smoke gun and air pressure.
If you seal a fan to a window and suck air out of the car. A friend with a smoke generator outside will pinpoint where water can get in. You can pressurize the car and do it in reverse too
https://www.musclecarparts.cc/1967-1974-mopar-a-body-glass-channel-weatherstripping---curved-like-factory-requires-cutting-%26-guide-holes-25375
Lots of sellers sell this same kit so find a seller that has a good price and service.
It requires the removal of the door glass and vent window...
Your last photo shows the parts in the vent window frame are gone, there are replacements available.
My dad bought his (my) Dart from Claud Short Dodge in Santa Monica in Feb of 67.
His log books show water leak after water leak right from day one.
I had the windshield gasket replaced...
Because anything that contacts the needle drive and the spinning magnet (attached to the speedo cable) will cause needle bounce or other issues
Cleaning out the areas CAN help, there can also be metal particles stuck to the magnets.
Btw @dowboy1970 there are point sets for small block dual point and a different set for big block dual point.
This is from 67 parts catalog
65 will have similar