Any of these bikes can use magneto ignition if you want to use 1920's technology in a 1970's machine, but you still need an alternator or generator to provide lighting power on a street bike. I think you mean using a permanent magnet alternator/generator which can work without a battery. It is possible to modify any SOHC4 to have a permanent magnet alternator but the job is never easy. Possibly the 350/400 has a crank end taper that fits another bike's permanent magnet rotor (CB77?) directly where the other models require more improvisation and machine shop work to do it. I don't know, I never had a huge problem with the stock system. You can use a small sealed battery if you lose the electric starter, the weight loss would be comparable.