Well, I had a very pleasant phone conversation today with Mr Ron Zacka, CEO of Parklands Trading and son of the founder. He recalls the "King" which he confirmed is an Oleo-Mac mower that went under a number of brands in Oz, and is powered by an Efco engine, however it wasn't Parklands that imported them it was actually Cranford Products, a now defunct company that was headquartered in VIC.
Cranford Products was the distributor of Oleo-Mac up until 1992 when Parklands took over. (In 2007 Roy Gripske & Sons Pty Ltd (QLD) took over the Oleo-Mac distributorship.)