I put a 68-72 12 bolt in my 65. I am using the rear flex bracket (offset) that came with the 12 bolt. Im not sure what rear flex line to get. The old one from the 12 bolt had the block attached to the line and a hole in it to screw into the bracket. Is this the right bracket? If so, what year hose to I need for this.

That's how the rear hose is set up on my '70.
If your original doesn't work, I'd say get a '70.

-Dave