The crack did not go all the way through but let pressure through above half throttle and pushed under the head gasket and would seep coolant back the other way when shut off. I replaced the sleeve and all is well now for many years.
I had a D282 that was getting coolant in the oil and It had a cracked cylinder sleeve. It would also get pressure in the radiator if run above half throttle.
If you put a turbo on it already and did not turn up the fuel, that is what should be done. As far as hurting the hydro, your power is going to the pto not the transmission so it should not hurt a thing and the 1066 hydros had turbos on them anyway.
These were made just after the merger, and the Mogul was designed and built by the McCormick engineers and the Titan line was engineered and built by the Deering team.