You will need a large ring compressor to compress all the rings on the John Deere B piston. The oil ring is at the base of the skirt and the four compression rings are near the head. Don't tell anyone, but I found this one at Harbor Freight. The ones I saw at tool and auto parts shops were short and wouldn't cover all the rings at once.
I found that it was easier to insert the piston into the cylinder to the oil ring and then put the ring compressor on. This allowed for an easier start of the piston into the cylinder.