We are looking for a standard here it seems, at least on the 427 SC variant of Cobras that almost all of us here in Australia seem to have. Pity, we don't have more Cobras shapes in this country. I really liked Rick Parker's 289 slabside in the US, in another thread:
This photo on the FF site shows the current rear.
Component Cars Australia
I seem to recall some criticism of the DRB a year or so ago as it was too 'droopy' in the rear.