You can't do this with a single "normal" lens.  Because the beam width needs to be 4.25 inches you need a lens wider than that (which is huge compared to normal optical components).  The focal length of the lens would need to be 4.25 in/(2*sin(60 degrees)) ~ 2.5 inches = 63.5 mm which is smaller than the width of the lens, and you can't really make normal plano-convex lenses like this.  

You have two options -- you can use multiple lenses (one lens to collimate, then a pair of lenses to step it up to a larger beam width), or you could also get ok results from using a [Fresnel lens][1] -- one that is fairly close to what you need is [here][2].  The second option will probably be much cheaper, but may suffer from more aberrations.  


  [1]: https://en.wikipedia.org/wiki/Fresnel_lens
  [2]: http://www.edmundoptics.com/optics/optical-lenses/fresnel-lenses/fresnel-lenses/32683/