Chlorprothixene is an dopamine antagonist as well as an H1 antagonist so it should work?? As far as my limited knowledge goes Dopamine receptor antagonists such as Meto or Domp work better than anti-histamines.
Mirtazapine is a 5-HT3 receptor antagonist and has shown anti-emetic effects, although it doesn't block Dopamine receptors as far as I know and Idk how it compares to drugs doing that.
My guess is Chlorprothixene is probably fine, though Mirtazapine is probably more for long term treatment of nausea any may have a weaker effect?