I wondered at the response of Mssrs Peter White & Troy Courtney.. are you folks ready to cut a full length of new threads in a chromed steel steerer tube? At CDO, I am not willing to use our VAR or Campagnolo (especially) or even Hosan thread dies on such a time consuming and potentially damaging task!
Also, in the real world of use, rather than the theoretic world of ideal steering geometry, bikes can have an amazing tolerance for different fork offsets and blade lengths. Many Italian bikes of the 1970s + used a set fork offset for every size in the line, most often 45 mm.
Dale pragmatic Brown
Greensboro, NC USA