I have had another look though my result sheets and see I called the car a Kiwee KC in the final round of the 78/79 season but I was probably messing around.
If it was my choice ..... as we may see the day where all 3 cars are running at the same meeting I would go for Trident Mk1, for the square tubed car, Trident Mk2 for the round tubed car as it is effectively a MK2 version of the square tubed car.