SBC, Haisley & EEP all make good dual disks but SBC seems to back up there clutches better than anyone else and that goes a long way. JR Adkins or Olee Poole can get you some good prices on a south bend or you can go to Peter directly.
If you get a dual disk, remember to upgrade the slave/master cylinder on the clutch (from a 12valver). EEP has them and SBC I think is starting to carry them. if you choose to modify your own slave/master cylinder for use with a dual disk, there is a member on here whose name is Jeff that can send you instructions on how to do it (forgot his screen name but i have his email).
Dave