Guess I need to start a new thread on the two different styles of seals and plates used for this purpose from the 65-66 style your car has to the later "67" and up style used during the year.
Both are related to the style of steering column and steering box.
Example below
With that said it appears that the engineers designed the plate so that the inside opening was well under the inside radius of the firewall opening and with the lip pointed forward into that opening it forced the seal to turn back towards the interior of the car creating a better seal for the steering columns outer tube as shown in the examples below. This orientation of the plate allowed for a bellowing or curving of the seal towards the engine compartment and then, around the column, back them inward and up the steering column as designed
Believe that is what the pictures below are indicating - that the plate was originally installed as the drawing shows
In the upper right it appears to me that the seal was pulled tighter up the column and against the inner plate. Notice the sharp edge shadow of likely the edge of the plate facing in towards the steering box. While in other examples the gasket was not pulled as tight and they produced a softer curve that was likely the plan