Here are some examples for you to compare. Could not find any NJ 68 examples so posting San Jose and Dearborn instead.
Dimmer switch cut outs appear to be an attempt to be somewhat roundish and not real pretty often but not always
Some examples of carpet screws located at the outer edge of the front carpet edge.
Picture of the floor pans with no screw holes on these examples at the inner carpet edge near the tunnel and an example of the location for another example for the outer edge screw. Don't believe there was any guide to where the screws were to be installed exactly so with a self tapping screw just somewhere that would work or possibly hand punched then followed with the screw
Hope this helps