I didn't see the Gutbuster Butcher With Cauldron listed with a size. It's blank. Here to report that it fits nicely onto a 105x70mm oval. However, if you're going to convert(glue it on top) the old rectangle it came on you might want to consider stepping up one size as the square corners will overhang the 105x70 a tad.
Player:
Location: Tecumseh, MI, USA
Name: Evan / Yankee
Contact: burrevan288@gmail.com or forum pm
In addition I didn't see this up there yet:
GW Store
Location: Ann Arbor, MI, USA
Name: Warhammer Ann Arbor
Contact: Warhammer Ann Arbor- Facebook