It's a matter of how much height your trying to gain. You could go with a stem with a great angle which would raise the bars but depending on the length, the bars would also move horizontally. A bit of geometry wrangling would let you calculate the effect. You might have to move to a mountain bar stem (25.4mm clamp diameter) like the Salsa SUL to get enough rise.
This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.