40 - 60 pound Spectrum is the way to go. Your 6 foot leader line should be 40 pound. I prefer 50 pound leader and rigging. Spinning rods are useless here. Please leave these at home.
Conventional rods are the ticket.
Patience is golden with this type of fishing. Blackfish sometimes warm on a spot before they bite. Don't give up on a spot right away. If you get to your honey hole at slack tide, the blackfish will most likely have lock jaw. As soon as the outgoing tide starts, they'll go to lunch on your bait.