You will probalby find out that the switch you remove actually works like the one I had on my 91 ZR-1 did. I was having to put in a new clutch (too much autocrossing
)and decided to look at replacing the switch while I had the transmission out of the car. The switch was good, but they are known for not being depressed far enough by the ZF transmission to turn on the back up lights. I was able to get mine working when I reinstalled the transmission, but it then quit again a few months later.
There was actually someone on the ZR1 website that had made up a specially modified tool to reach up and remove the switch that was continually getting passed around to others for trying to fix the problem in their cars. You may have to do like most owners of this transmission and live without backup lights.