The Model A crowd argue that mechanical brakes in good shape are as good as hydraulic brakes.
My experience with Model A brakes is that most of them have worn tracks that the rollers run on, so the wedge that expands them can't push the shoes apart. I solved that issue by welding the tracks on the backing plates with a carburizing flame on OA (kind of by accident) and machining them smooth again. But they were too hard to cut them on a mill, so wound up grinding them smooth. Then my brakes were "adequate". The emergency brake on the Model A used a toggle type linkage to expand the band, and it was very effective. Easy to lock up the rear wheels.
It totally would depend on the design of the mechanism whether mechanical brakes should be restored to original condition or replaced by hydraulics.
