Unless it is a modern CNC lathe, setting up a taper requires a fair amount of trial and error to get within a half a degree.  Best to start with a piece of something cheap and get the lathe dialed in before making the production run.  For what it's worth, I have had better success by making cuts only in one direction (big to small) rather than cutting both ways. Shipping will be a nuisance, but Precision Machine Tooling on Oahu could make what you want with no trouble.