Yeah, if using a universal fit shift boot and flat trim ring like they sell at Autozone, the carpet edge can show unless you carefully cut the carpet right along the line of the screw holes so the screws hold the carpet edge back. Agree that you will distort the trim by tightening.
The '64-65 used an upper and lower boot and a flanged trim ring. The upper "nested into the lower on console cars. Only the lower boot was used for non-console cars.
Here's a couple pics of a '71. They simplified it by forming the boot with an upper and lower sealing flange. One goes below the carpet, one above with the trim plate retaining it. As you can see, you can install the trim ring on top of the carpet as the flanges hide the edge of the carpet.
Pontiac used the '64 lower boot only on non-console cars. The factory ring is flanged so the carpet can be hidden behind the edge of the trim ring.
