This is intersting that they want bows that really function for this shoot. Are the actors going to be able to handle even reasonable draw weight for multiple shots? My understanding is most movie bows are props, not the real thing. That is true with Scropion King and the Lord of the Rings trilogy.
Are these going to be hero props, or will they make copies for various other shots? A hero prop, if you have not heard the term, is a prop used for close ups. For longer shots, they use similar props that don't have to look good, or ones they destroy as part of the film's story. The sword used in Robin Hood (the horrible Kevin Costner version) was something like six different swords. One was heavier and more cumbersom to make the evil Sherrif look weak and silly during the sword fight at the end, if my memory serves me right.
Dane