Sand Force is useless without Sandstorm.
If you do have sandstorm, Iron Head would be preferable for taking out its Ice/Fairy weakness, as M-Chomp is rather fast. Preferably, Dragon Dance is my move for raising Attack and Speed and when used with Simple Beam in a double battle, M-Chomp is a terrifying sweeper. Simple Beam from an ally doubles Dragon Dance, making it twice as deadly.
But why Fire Fang? earthquake takes care of Steel Types, so Iron Head should maybe replace fire fang.
good coverage, plus a stat boost to clean up.
That's my suggestion
(Iron Head only if you have sandstorm)