Try AFAM or Vortex Racing. Sprocket Specialists can make you one upon request, but it'll cost some extra bills for machine setup.
You will run into all those issues that you've mentioned. You will also offset your speed (will read higher than actual), therefore you will also rack more miles on your odometer, than actual.
But you know what? Doesn't seem to bother many people any.
Do a search for sprockets. If I remember right, there was a really good thread about this a couple years ago, with all the equations and all! If someone remembers that thread, dig it out and post it, that'd be great!