PER-SIN has become flooded with LCCs and the biz class seats are scarce.
Scoot biz is really PE but very reasonable cost, however it lands at 1am in SIN. flyscoot.com
Air Asia via KL has a proper biz class but the times are again awkward.
SQ biz awards to/from Australia are only released 2 weeks ahead these days.
Could ask BA to look for a Malaysian flight via KL now they are in OW, if you're up for it.