Seems to me that it might not need any/much remedial work at all.
In addition to JS, oil pressure when hot with correct grade of oil?
You may have some small end rattle or timing or valve clearance due to wear.
If the tractor is not worked hard ever, the oil consumption may not be a problem or may just be going down the valve guides.
You may need a higher grade of plug or it may be running too rich (the sooty plugs).
From a long distance, I am mystified as to your reasons for a major overhaul.
Diagnosis and rectification as appropriate would seem to be a far more logical plan. The engine may have another couple thousand or more hours before needing a major. Interfering with seated components in an engine of that hours is not a good plan unless changing them out.