What else would I need?

To do it correctly you should install a disc brake master cylinder and a proportion valve but... You don't absolutely have to right away. Our first 67 fish, 9X3 drums out, 74 discs in, We had nearly used up the first set of disc pads before I upgraded the hydraulic side. I guess I should ad that a later model LBP 7.25 rear was going underneath. New rear brakes incl' wheel cylinders, hose at differential, etc.., so master cylinder and perf' valve all in one final stage of upgrading.