Bloodbeard:
Just found this kickstarter project:
Making 28mm heavy support weapons on gun platforms in a steam punk theme. Not all of it will work with chaos dwarfs. But I see both a dreadquake and a deathshrieker possibility. Only a few days in and already funded. 
Dreadquake:
Deathshrieker:
And a machine gun - what could work as a magma cannon:
Size comparison to standard 28mm human
14£ for a single machine, 40£ for three. But there are still early bird specials for 12£ and 35£.
