Will light switch for a 56 ford work on a 55 ford when converting 6 volt to 12 volt system?

Can someone give their advice on converting from a 6 volt to a 12 volt system? Will a 56 Ford light switch work?

Sure. Switches are not bothered by small changes in voltage. Current is what can cause problems with switches. The current should be the same or less going to a 12V lighting system.