The Ogor and Leadbelcher bodies are identical, it's just an arm and head swap - they fit perfectly. The set should come with the Leadbelcher cannon sprue which would give you enough bitz to make 4 Leadbelchers if you use two additional Ogor bodies. The existing plastic Ogor kits are all compatible with each another, even the riders on the big beasties have the same arm, head and gutplate fittings as the various Ogors on foot.