Looking at the pics, a couple of things I need to point out. First, I didn't realize the age of the engine you are swapping out. You may have a difficult time finding an engine that will fit in that small footprint. Not impossible, just going to take some time. Second, make sure that you get the same length crankshaft, to accept that double pulley. Third, your new engine must have a charging system, to charge the battery you, plus you may have to do some rewiring to fit your tractor.