No, I am not sure. I was just looking at the diverging white forewing streak. Some O. dirempta have a white streak, and in some the white streak diverges toward the margin. I think that streak of O. beltista diverges more, like this specimen. Other characters such as antennae may provide better diagnostics.
I found an image of O. beltista on iNaturalist showing an asymmetrical biipinnate male antennae structure quite different to this specimen and to the reference antennae for O. dirempta in the Moths of Victoria key.