By the time you swap engines, you have almost the same amount of labor as just overhauling yours. You have to pull the camshaft to swap the front plate to make it fit into the tractor. Basically dismantle the whole engine less crank and pistons, and then re-assemble.
As a dealer, if you aren't sure of your ability to swap the engine, then get yours rebuilt. We have done this in the past for customers that refused to rebuild them, and it was basically the same cost....and you still have a used engine.
Feel free to give me a call if you'd like, I would be glad to help you anyway I can.
Mayer Farm Equipment
Jeffersoncille, OH 800-996-2937