I think it was an image thing. Chrysler Australia needed a hot two door to compete with the Ford and Holden hotshots of the day.
What they achieved was WAY lighter, quicker accelerating than the V8's( I know I'm going to cop it for this, but look it up) and better handling.
The Charger was...
It's a VH Valiant Charger, Aussie assembled, US designed. It is carrying the 770 badging at the back, hence the padded vinyl quarters and doors.
Wheelbase is only 105 inches, based on the A body, but with a bit of B thrown in too.