Diesel Fords of that era, had cooling systems that actually turned acidic and could eat holes into the block, internally, low in the water jacket, if the coolant wasn't changed or treated regularly. The gas versions didn't have this issue.
As far as which one is best? Either. But make sure there is Power Steering if you want to add a Loader, PTO Pump help for a Loader, because the internal Hydraulic Pump doesn't have alot of flow. Stay away from Selcto Speed, not because it isn't nice, but few know how to set the Bands.
CAV Injection Pumps are easier to rebuild than SIMS Pumps, but need rebuilding more often.
Just from an Old Ford/New Holland Tech, in the 80's