Your car has one of the best braking systems of any Classic car. You just need to fix your existing brakes. I would never consider trying to modify the brake system you have.
My 836 can lock it’s wheels with a firm application of brakes. You can’t do any better than that.
The limitation for stopping is the small tire-to-road footprint of the old tires, not the brake system itself.
I suppose it would be possible to install hydralic brakes, but it would be so ridiculously expensive, and it would destroy any antique value your car has.
The Stewart Warner Servo power brakes that your 836 has uses the momentum of the car as the power to apply braking force to the brake shoes. With this system, a very light application of the brake pedal causes the power servo to apply the rotation of the driveshaft to apply the brakes. The result is a very powerful braking action.
The usuall cause of poor braking in the SW system is the servo’s brake-material lined disc. When this disc [which runs in transmission oil] wears down to the rivets, it’s friction is greatly reduced, and the power brakes will feel weak. No addtional amount of foot pressure will make any difference, the brass rivets don’t provide enough friction.
So first is to reline the servo disc, South Bend clutch can do this for you.
Next is the brake lining on the brake shoes. You should not use modern type hard brake lining. You must have a medium-soft to soft woven lining on your brake shoes. A modern lining doesn’t provide enough friction with the available braking system.
An inspection of your brake shoe material, and a check of the brake linkage for excess play is needed, then possibly removal of the driveshaft and the back half of the brake servo to access the servo’s disc.
Hope this helps..
Greg Long