I am throwing this idea in on this problem, but admit I am by no means an authority.
Now after seeing the pit location, I assume rebuilding of the pit will be necessary. Also I don't remember the size of the repurposed table, but this too will need minor adjustments. So, would it not be the case that to figure the pivot point you would start by locating the center line of track for each stall. Their intersection should show the pivot point. As the likely hood that the stalls will not align perfectly, it should be close enough to be able to manipulate the pivot point. Then you can rebuild the pit to fit the table and then you can relay the track into the stalls.
I would think that with only a building and an earthen pit this should not be to difficult to build because there is a lot of room for adjustment once adding the final details.
Am I close on my assumptions?
Phil