Renew pistons and liners fiat 880 5

[fiat 880 5]

Good morning,

We bought a fiat 880 5 with the piston stuck due to water on top of the pistons ( rainwater via exhaust)
It was outside for 10 years but put there running.
I took out the nozzles and looked inside and saw the corrosion.

Question is : Has anybody trieed to take off the sump without splitting the tractor.
For me i donot know where the fittingpins between the parts are.

please advice.