The model A electrical system switch saw the full load of the function it operated. Modern electrical systems use relays, allowing the function switch to operate in milliamps, with the relay handling the actual amperage required to operate the lights.Using the modern design I’m able to run my entire lighting circuit with a single toggle switch and use a micro switch as a brake light switch.
If you just want to use a modern switch in place of the original switch be sure the switch can handle the amps required to run the lights, I use the 30/31 steering column support bracket to mount an instrument cluster