I think that 1983 was pre-radar in Darwin - you remember that it was when anybody could fly drugs into Australia from Indonesia because we had no means of detecting them. (Actually I'm not sure we can now - after all they probably ignore the ADS-B mandate). So pre-radar the C130 presumably wanting the same track as Dick, would have had to wait for Dick, on an amended route, was outside a lat/sep point. If Dick could be given a track that was more than 40 degrees different to the runway heading that would not apply. The simplest way would probably have been to turn Dick back over the field to depart behind the C130, then everyone departs on track. In the US VFR Dick would have been traffic information in Class E airspace, or as it was known then, VFR exempt.
Crazy but that's what we did. If Darwin had been uncontrolled the C130 driver would simply have taken off and kept his/her eyes open for Dick's helicopter.