That engine is rebuildable unless it has a hole in the block. Parts are available if you look. I saw one for sale that had a Tecumseh snowblower (Snow King) engine but the tractor had been cut up to make it fit.
Sears used HH100's and HH-120's in their LGT's if you have to go look for a rebuildable core at a boneyard.
They made the 112 with a Kohler K241 as well as with a Tecumseh HH100 but they used different frames.