Looking for a 1976 A-body A38 police certified speedometer

A good friend of mine has 76 4dr Valiant, that I believed originally was owned by a lady who rarely drove it and in incredibly fantastic condition. They are in the process of making it a A38 Clone or Tribute, as that is what they have always wanted and have had no luck actually finding a real one for sale. So they are making one. One of the components they would like to find is the Speedo that says "CERTIFIED". They are attempting to actually locate a real one before settling for having to make one. So I told him I would see if I could help track one down. Thanks