TC:
The "original" location for the battery kill switch is the center of the rear cockpit cowling. The idea is that in case of serious accident, a track official could easily find and deactivate the switch. I decided not to go that route, as I did not want the switch in such plain sight.
I elected to install my Lucas key by fabricating an aluminum bracket that mounted the switch to the inner downleg of the battery rack. Now, I am using two original Rebats with the original dimension rack. If you are using the Kirkham unit designed for the gel battery, I still think this method will work fine.
Check out my gallery for a photo.
Bud