Could be but I would doubt it. In that engine if the guides were that bad it would be hard for the valves to hold an even 90 pound pressure.
I would sooner think that it had over heated and the oil ring got seized to the piston to let oil get by.
engines like these without water pumps used in factory mules would often over heat from not paying attention to water levels and start smoking. They would replace the rings without any other repair and put the mules back in operation.
Really hard to tell if that would be the problem without being the operator from the start though.