PER-KUL RT used to be my regular route before Covid. MH125 uses the B737 with the recliner seats 2-2 per row. Not the most comfortable seat in the fleet but it is doable for the 5hr 30min flight. Especially since that flight departs KL in the morning. MH127 normally uses the A330, could be either the -200 ex-Air Berlin frames with the narrow seats (if this one and travelling alone, go for seat 1A. Heaps of room in front) or the -300 with MH lay flat seats. That flight departs KL around 8pm, getting into Perth after 1am.

Unfortunately with January you’ll be running into families and students returning to Perth after the holidays. I’ve been able to find MH seats when I need them using both Avios and Asia Miles, so they are around. Probably best for Jan if you keep monitoring, MH is reasonably consistent in releasing seats if the loads are low.