65 El Camino parking brake almost there

Great help from everybody on various work on this project. Emergency Brake is close - I have put a new assembly in (cables underneath and hooked into Brake Assemblies and pedal under dash) - the problem is that in the brakes only the passenger side brake assembly has the arm that the cable attaches to push the shoe out - the driver's side is missing and auto parts do not have it for a 65. So I attached the cable to passenger side brake and put the cable into the brake drum on driver's side (but not attached to anything) - when a step on the parking brake I move the brake on passenger side and it applies pressure but It does not feel like the brake will hold - is the drivers side not being attached giving me too much slack to get enough brake pressure on passenger side? Suggestions ?

Thanks,

Chuck