Ken, you wont find a Gremlin, you can put that idea out of your mind....
But for whatever it's worth, the measurement from the centre of the rear axle to the very back of the car is 65mm (just over 2 1/2"). That's how much rear overhang you need on a shell.
There aren't a lot of these chassis out there yet so you might just have to wait and see as people try them.