Ho boy. Comments after you already cut the shaft. When I split my last tractor, I pulled the sheet metal and all the obvious stuff. I stuffed some wedges into the front axle to keep the front 1/2 from tilting. Just in front of the split was a bottle jack to hold up the front.
The back 1/2 was held up, and rolled straight back, with a floor jack.
I also did it on plywood on top of gravel. Your split is the next joint back requiring sealant upon reassembly. I would suggest Gray RTV. Similiar to what is used to seal oil pans on transmissions and such.
Beyond that a wedge driven between the halves to sepearte them will be in order.