No to both, as far as I know.
If they ever looked at their own four-stroke, it would have to have been before the early 1970's.
But that's a very different level of manufacturing technology to their full-crank 2-stroke engines, which were what they then made.
The Whitlam Government took the razor to the import tariff barriers that protected local small engine manufacture [among other local manufacturing] in 1973, and the local 4-stroke small engine manufacturing plants [who mostly made overseas designs under licence; e.g. James N. Kirby & Co with Lauson/Tecumseh, and Norton Villiers Australia with Villiers] did not survive long afterwards. With them went their two-stroke products, and at least one two-stroke only manufacturer went too - Pope comes to mind there.
Victa was soon the only remaining local mower engine manufacturer, until the 1990's era, when they became an assembler of mainly Chinese-made contracted out parts.
Line trimmers only really came on to the Oz market in the early 70's, and the Japanese makers then had high quality products that would have been very hard to compete with, especially with tariff protection gone.
Victa's smallest capacity engine in that era was the 85cc Compact/Lightweight one. The core engine is reliably rumoured to have been made by Bombardier in Canada for Victa, along with the 170cc Twin engine.
