Enough diversion, back to Brad's original post.
Even though I strongly support CD, I would prefer to work with a local rigger for this. My boat is an '82, and who knows how the rigging has diverged from original production. A local guy can come out and compensate for all the nuances, even if it only comes up during installation. He would be completely responsible for seeing that the job is right.
If you don't have access to a local shop, you'll have to go with standard specs, or do measurements yourself. You may encounter some problems, but it can all be worked out, even with a remote supplier.
Best of luck.