I have had a lot of experience with replicas, and played enough originals (including Hauser 1, II, III) to venture a couple of observations that I hope are useful. The first is that there are a lot of blue prints of Hauser, Torres, etc that are available to any luthier who cares to make a copy, that said even the most detailed and accurate blue requires a lot of interpretation, and the more experience a luthier is, the more aware he will be of just how much needs interpretation. There is a second approach, which is less concerned about "authenticity" than sound. Luthiers who use this approach build to the sound they are trying to capture-- while making a nod toward its looks. In the end, every guitar ends up reflecting the tastes, intelligence, sensibilities, and skills of its builder. So, when I choose a builder to make a copy of a particular guitar, I pay very close attention to the kind of guitar that he regularly builds, and look to someone whose guitar seems to share the same sort of general character--as it will be easier for him to make the journey into another sound space than one whose own guitars very different.
James, Zavaleta's La Casa de Guitarras