I've updated the utility to allow you to select to either import the fighter's current record or choose a year (as far back as 1900) which will serve as the last year of records to import.
For example, if you're curious what might have happened had Ali been allowed to box between 1967 and 1970, just export fighters from that era, choose 1967 as the last year of import and all of the fighters have the records they would have had at the end of '67.
You can download the updated utility
here.
Any problems or questions, please let me know.