There are some pictures at http://gardentractor...one-9186/page2/ - scroll down
I guess I would need to see the engine
As you can see there really isn't anything that can be removed to reduce the height - if the fuel tank was and issue I could certainly convert the original tractor tank (which I would plan on doing after the rest of the conversion is completed). The exhaust could be replaced relatively easily if it is an issue but I will wait to see how it fits into things first. When I have pulled the Kohler engine I plan to make some good comparison measurements and post them here in case it might help others in similar situations.
These engines are kind of deceptive in size. I think because they look similar to gasoline engines we are used to we tend to associate them size-wise in our minds. They really are very beefy and somewhat larger overall. Not big enough to be a deal killer as candidates for repower projects, but certainly requiring a really big shoehorn.