Okay I am sharing this idea I had here because I realize I will never have the time or money to do this particualr conversion.
Renegade Collossus
Bascially you take a Basilisk and then you add this to it.
Warriors of Chaos Hellcannon from WHFB
The Hellcannon should be about the same size and if far more chaosy then anything else there is. Look at all those souls that make up the barrel. You could even keep the Chaos Dwarf crew if you wanted to. Just loose the wheels and kepp the barrel and TADA!
With the new IG codex and a set of FW renegades, I see more and more chaotic guard armies. Thought this would be appropriate.
If someone does this, please let me know.