Jeff,
Here is an old thread on the topic:
http://j30.us/ubbthreads/ubbthreads.php/topics/3795/Rudder_Rebuild.html#Post3795I have a used, class legal rudder available that is detailed in this link:
http://j30.us/ubbthreads/ubbthreads.php/topics/11322/Re_J30_rudder_and_dodger_wante.html#Post11322It is shown below being repaired after storm damage, and has been replaced with a new rudder. It is now fully functional and gelcoated, but no longer used.
It is sound as I drilled holes in the bottom about 5 years ago and let it dry over the winter. All I got was dry core. The holes were epoxy filled. I will sell it for $800 plus the shipping. My new rudder cost $2000 plus shipping. I could get packing material (bubble wrap) and build a cardboard container for shipping. It is considered "oversized" and would be approximately 80" x 20" x 4" packaged weighing approximately 80 pounds. There is a local Staples store (Zip code 02840) that is a UPS shipping drop-off and I could ship it from there. What I suggest is that you would prep-pay the shipping with UPS, or another carrier you choose to the address you desire.
You would probably want to epoxy fill and redrill to match the holes in your mounting hardware, unless by chance the have the exact pattern as my hardware. You also would probably sand and apply matching gelcoat for your boat colors.
If you're interested in this, let me know.