Nice idea, but it's got a catch! I won't promise anything at all, but if I do try to sculpt one and find someone interested in casting and selling it, it will most likely be first in some years time.
The catch is, the asscannon would be visibly based on the old sculpt, but much updated. Think scaly areas, spines and skin texture. Think a much more detailed barrel mouth (perhaps a rune-inscribed metal barrel brutally projecting from the live daemon's torn behind?) and think shackles and chains fettering it to the ground. The Daemon would probably have a muzzle.
It would also have crew without twisted viking knight look, but instead with masks and a hat for the leader, scalemail, leather straps and tools. Or no crew at all for lawyer's reasons.
I'm not sure there'd be much interest in such a model. We'll have to see later on if I indeed try to make one. If I'm to make one for myself I might as well make one for everyone else whilst I'm about it.
The nature of the proctiles can be debated.