I've read that plug wire ends can contribute to misfires in an M119. Should the wire ends be replaced periodically? Are they separate from the plug wires?

Is there a general replacement mileage for M119 caps, rotors and wires?

On a stretch - is there a way to convert an early M119 to the one coil per plug set-up of the later M119? Maybe put little fans in place of the rotors so the engine looks like an airplane

Thanks,
Sixto
95 S420
87 300SDL