I would definitly replace Inferno for another move unless this is in a double battle and you have a No Guard Machamp beside you. Otherwise, change it. Here are your options.
Flamethrower- 100 accuracy but with the lowering of the BP to 95 and a 10% chance to burn opponent.
Overheat- A great move on a Specs switch-in. 140 BP, 90 accuracy, and a drop in power, but like I said, on a Specs or Scarf Chany that just switched in and will switchout after presumebly OHKOing, it works.
Fire Blast- The medium move here. Not best accuracy not best BP. So 120 BP, 85 accuracy, and a 10% chance to burn opponent. Not bad, eh?
So overall, go with Fire Blast. It is the best rounded move with great power. And it will hit almost as often as Overheat but without a stat drop.