Welcome to the 12 Discussions, Steve, and to EC12Net. First of all, where are you getting a hull and deck? I hope it is not an unregistered Dumas.
The rudder situation depends on what hull you have. If you have a Hull Standard that has been in production since the 90's it will be easy.
If you have found www.ec12.info
in your Internet travels, you will see what the masses are up to. The Ozmun swing arm winch has be used by those that like low complication in building with good performance. The majority are buying the RMG 280DL and the new recommended drum is the 30zs7 by RMG. At the above website there is a recent comment on this new drum in Bulletins.
Give us some more information on the hull and a follow up will clear some things up as to where you should go.
BTW all, Steve is in the Sooner State club Victoria fleet at OKC.