Another issue to consider.  I once talked with someone who was designing nuclear reactors.  They had a similar requirement to archive their design simulations.  But in this case, part of the requirement was to pass some standard simulation tests (in FORTRAN, of course).  He was complaining that these programs had bugs and didn't give the right answer.   So they ran the corrected programs to make sure the thing would not blow up, and then tweaked their parameters so it would pass the buggy program that was written into law...

Steve