Brake Pedal Compatability

Morning Guys -- got a series 1 with no brake light switch, fitted an MB one and then realized that the brake pedal doesn't engage with the switch plunger -- can you fit a series 3 brake pedal to a S1 (hole centers & fittings the same?) or is it a bodge (amendment) on the S1 pedal with a wee block tacked onto the pedal to engage with the switch plunger? -- Cheers G