I'm a fan of the Shibaura Fords / NH.  I've owned several, my brother has two of them, Dad has one.  From 1979 to mid-2000 models.  No issues with reliability on any of them.  They are well designed for easy maintenance and operation.  700 hours is nothing for the 1720.  The xx20 series Ford / NH tractors were built in the transition period between Ford and NH.  They are built heavy - like the Fords, but quiet and refined like later tractors.  Perfect attribute mix for a great tractor.  If it is the factory branded loader and all sheetmetal is good with no rust or other problems, I would try to make the best deal I could make and then take it home.  With proper care, that machine will be operated by your grandchildren someday.  Good luck.