So you are saying that FTM allows for more than 248 characters in a "description field"? If this is the case I would change these to NOTEs.
For example when importing an OCCUpation via GEDCOM the value following the "1 OCCU" tag sould only carry an occupation designation, for example, Carpenter, Baker, etc. GEDCOM says this value should be 90 characters or less, but realizing that most software would never top the data entry this short, the value should never be so long that is value needs a CONC/CONT or goes out to thousands of characters as if you were writing notes about the occupation.
SSN should only carry a SSN number which can't be more than 11 characters long in a GEDCOM.