It looks like your Gunnm cel is the real thing.  
I used to have a cel similiar to this, just a few 
frames after.  I remember the line quality, color 
and airbrush effect looks exactly to the old cel 
that I had before.  The pencil sketch looks fine 
to me too.  I have collected cels for many years, 
based from your scanned image, it looks as real 
as it gets.