A slightly different Mk.4 chassis.

This is Kym's 4A in its glory days.
And below is a photo of the very naked chassis as Kym prepares for a comprehensive rebuild.

It has twin rollover hoops, although the left hand one has been chopped off some time in its career. None of the Mk.4 owners have seen this on any other chassis. Don Hall, who ran a successful speed shop in Perth in the 60s produced these photos taken in the Bolwell "factory" way back when.

They wouldn't have been water damaged if Barry didn't have them in his door pocket while driving his Mk.4 in the rain. Anyway, it might be fair to assume that this is the same car.
Anthony, this would be your old Mk.4.