The rear of my replacement dash has the following:
#1: routed out for the Hazard switch, which is a bigger body switch than the rest.
#2: Fan switch has a shim piece glued to back to pull the switch into the dash so the center between the rocker ends is level with the face. You can always stack washers under the mounting ears to accomplish the same thing; no one except you will EVER know, because 1) it's at the top of the dash, and 2) the mess of wires underneath will never be inspected at a show. And if some judge is crawling around under your dash...he (or she) better be a good friend...)
#3: Light switch is routed out so the fixing nut on the front has enough threads to attach it.
The ends are routed out to account for the thickness of the air vents.
HTH