repair the master cylinder properly, set the brake servo pushrod properly, make sure the residual valves on the master cylinder are not jammed or blocked with rusty brake fluid.
service the calipers with correct grease and make sure the pistons are clean and free to move, Redo the rear brake drums properly (I think 80% of mechanics dont even know how to repair them anymore) - and flush the fluid out with the one man bottle bleed method.