This.
Caliber is the least critical componant. Leopards are thin skinned and small- boned.
That said, there are fellows that hunt Deer with a 300 Weatherby. Shoot what you are MOST comfortable, and confident with.. from 243 and up.
As is always the case...it's not the bullet...it's where you insert it.
Not to be glib, and being aware that, in the case of Leopards, the primary concern is a DRT result...
choice of caliber won't guarentee that.
The hole may be larger.. but if it's through the guts , or misses the vitals, things will still get sporty.
A Leopard properly shot with a 270 will die...with much less due diligence...than Spots poorly shot with a 375.
Best of African luck
Spike