My trans came out of a 1999 Camaro, the factory shift boot came with the setup .
This is the best picture of the boot I have installed.
I had to bend the base of it to match my tunnel and then just ran sheet metal screws into the floor to hold it in place.
Regarding the hole, I took my shifter off and taped up the hole in the trans, then lifted the trans up into position and scribed a line on the tunnel just around the outside of the square shifter mounting pad.
Lowered the trans, marked the four corners from the bottom and cut them out from the top. There was just enough room for the baseplate of the shifter to come up through the floor.
Also had to hammer up an area to clear for the reverse lockout solenoid.