Hi Jon, I have two 'hybrid' engines of differing output, But, they both have the later (May 1985 on) 126 rotorless distributor and twin dry coil. The system operates on the 'lost spark' principle with both cylinders sparking at the same time hence with one cylinder firing one spark is 'lost'. I believe that this system is more reliable than the true traditional item you mention, depending on the coil you need a ballast resistor in the circuit.
Ian.